A bad format, associates or not
The long lamented and dreaded ten-team World Cup has finally started and the arguments over the format are unlikely to cease until the trophy has been lifted if not after.
Strangely, within the general public, the argument over whether Associates should be included has been largely won. That doesn't mean the ICC will change the format, but the change from a decade ago when a smaller World Cup was the majority position amongst journalists to now reflects a growing realisation that the game depends on its smaller (actually, mid-sized) nations.
The question for this World Cup will be not whether it lacks something without the Associate teams, but whether a ten-team World Cup is what the ICC promised: the most competitive and exciting format, harking back to 1992; or just a money-making exercise by guaranteeing India nine matches.
Bertus de Jong has been a consistent voice for reason on the problems with a ten-team league-format World Cup and highlighted several on twitter around the narrative that such a long group stage brings.
My position has always been that there is no "right number" rationale for twelve, fourteen or sixteen teams over ten, eight or six. Obviously, fewer teams will have smaller gaps in performance between best and worst - though not necessarily more competitive matches. Equally obviously, large groups where a team can lose many games and still qualify, or be knocked out with matches still to play will have more dead-rubbers than knock-outs. To some extent the "correct" size of a World Cup is the one that allows all the members a reasonable opportunity to participate.
Almost ten years ago, when the ten-team tournament was first mooted, I wrote about how large a World Cup should be noting that cricket was far removed from the roughly six-to-one ration of Association Football and Rugby Union.
I also highlighted five myths that had been inflicted on the debate at that time:
- That more teams led to a longer World Cup when that is derived from the format;
- That low odds of victory for teams with lower ranks against the top teams is normal in sport;
- That cricket doesn't have sufficient depth for a large World Cup;
- That a larger World Cup has more pointless matches; and
- That the only purpose of a World Cup is to anoint a winner: that many teams participate to reach the next stage, or just to get there.
The third and fourth points are particularly important because they speak to the quality of the viewing experience. A few months afterwards, not satisfied with a hand-waving explanation I put forward an analytical method to look at formats. Put simply, the excitement inherent to a match is related to the change in probable outcomes.
There are beautiful match graphs for baseball that look at probabilities within a game. They show the probability of victory as a game progresses, and it is easy to see the difference between the very exciting (such as the Red Sox-Indians game shown) where the probability of each team winning shifts violently, and the not (Giants-Athletic) where it remains the same throughout.
We can assess the likely excitement of a World Cup match against a similar formula. In this case, the expected change in the probability of each team qualifying for the next stage of the World Cup.
Start with a simple example: in a knockout between evenly matched teams the probability of progressing for both starts at 50% and ends at either 0% or 100%. The change in probability adds to 1.00
A tournament where the expected change in probability was always 1.00 would be non-stop excitement. However it is also impossible. Between non-evenly matched teams the expected change in probability drops substantially.
In group matches the expected change drops further. An evenly matched four-team group has slightly less than half the excitement per game of a knockout at around 0.46. A calculation of the 2014 FIFA World Cup where teams are not equal produced an average expected change of around 0.35.
The perfect tournament would maximise the expected change in probability within other constraints - making sure each team plays a few games, getting enough content for television and so forth. The Cricket World Cup had a TV deal requiring at least 48 matches which rules out a simple 16-team with four groups of 4 and knockouts. But since 2003 it has had formats with at least this number of matches.
By simulating each round of previous World Cups we can assess them against how exciting they ought to have been. For the most part, since the small cups from 1975-1987: pretty fucking bad. Note that the key column to look at here is the simulated result, remembering that it should be as close to 1.00 as possible.
(Note that super-6 and super-8 games were not replayed. I have not adjusted for any additional interest factor from the first round matches because it is not clear how to do so).
1999 was the best World Cup format of recent times. Not surprising then that it is well remembered amongst everyone who wasn't an English journalist. 2007 was unlucky: the first round was actually exciting, but the second round was very long and it lacked take-off as the 8-team round-robin drifted over many weeks. Recent cups have also been poor by this measure, but the 10-team World Cup will be the worst ever for interest. And it is not close. We might get lucky with multiple contenders at the pointy-end but don't bet on it and it will be a loooong journey.
The best formats offer incentives to all teams. The recently axed World Cricket League tournaments with 6 teams, 2-up, 2-down were inherently exciting because the margin between qualification and relegation was thin. Teams expected change in probability was an average of 0.18 on both measures, giving a combined 0.36 per match.
It is for this reason that I landed on my preferred 20-team format that sends first place to a quarter-final and second and third to a repechage. First place in the group would be strongly incentivised as the winner can both skip the round of 16 and play an easier quarter-final opponent. So much so that the probability of overall victory is roughly double than for coming second or third place. More importantly, the depth of associate cricket is such that all five teams in the group would have a reasonable change of qualification in at least third place, removing the just-hear-for-the-scenery nature of most associate participation to date.
Based on rankings after the qualification tournament for 2019 a 20-team would have looked like this:
By running a similar simulation on both that format and a 32-team World Cup we can assess them against the formats to date. a 32-team World Cup would be a bridge too far - and yet still be better than a 10-team one! But a 20-team competition with a repechage and eleven knockout matches has sufficient uncertainty that it would be the best since the 8-team format last used in 1987.
Would a better format make up for lost revenue when India doesn't slog through 9 games over two months? Perhaps not, but it is not as far off as might be expected. A calculation of revenue based on Indian TV ratings indicated that the loss would be as small as 10%. And because it is based on a more reliable revenue stream than interest in one team, it would retain value even if India flame out early.
Given the flow-on benefits to participating teams in terms of sponsorship and recognition, a larger World Cup should be a no-brainer. But, here we are, almost 10 years after it was first announced, a 10-team World Cup.
Bring coffee, you'll need it.
1st June, 2019 22:41:34
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The WSC Transition
Bradman and Packer: The deal that changed cricket - Dan Brettig
Of the various revolutions to convulse cricket since its inception, the Packer one has garnered the most attention, and courtesy of several decades of Nine commentators, the most praise.
In its own way though, it was the least impactful on the nature of cricket. The International revolution, when Australia first defeated England in 1877 then, more importantly, followed up with tours and further victories in England was part of a continuum of touring sides dating to William Clarke's All England Eleven. But the Australian Eleven was a box-office draw like no other, and set the shape of international Test Match tours that continues almost unabated to this day.
The Board of Control takeover, from 1905-1912, that saw tours shift from the hands of Player's Elevens to national boards, concomitant with the founding of the ICC was less revolutionary, with almost no impact on the general public, but had enormous influence on the nature of cricket administration and player payments that eventually led to World Series Cricket 70 years later. More recently, the advent of domestic T20 has had more significant impacts on the shape of cricket than any event since the advent of the International game.
The ructions caused by World Series Cricket were significant, but short lived. The "peace treaty" was signed in 1979, but the public face of cricket, particularly in Australia was changed forever.
Most histories focus on those public changes: the white balls, coloured clothes and changed emphasis to ODI cricket. Dan Brettig's new book focuses on the private changes, and most importantly, the role of Australian cricket's most important figure: Donald Bradman. In doing so, it makes the Packer revolution look less like a revolution, and more like an extended transition from amateur to professional cricket board.
International cricket boards exist for three purposes: to administer the game, to act as a monopoly employer of cricket talent, and to sell a product. The Board of Control takeover was a victory for the first of these tasks at the expense of the latter. In the Board's eyes, the player led tours were reaping undue rewards from a product they had no right to control. It was a victory for establishment amateurism and sporting purity.
Bradman came into international cricket 16 years after the Board takeover in the dying days of players having control of their income. League cricket - with more in common with today's T20 leagues than County cricket - could still lure Sydney Barnes and Learie Constantine with reasonable salaries; and some of the older Australian test players had played with those of the earlier era of player control. Some, like Victor Richardson, had markedly different approaches on and off the field to Bradman who, despite an early run-in with the Board, was philosophically and politically inclined to the establishment. As a member (and for most of that period, Chairman) of the Board for 35 years he did more than any other to entrench a Board approach that focused on the administration of cricket at the expense of labour.
The graph above provides an inflation adjusted (to 2012) summary of cricketing salaries from 1893 to 2018, taken from Trove news articles and Brettig's research for the WSC/PBL era. The Players era pre-1912 provided variable but healthy incomes from tours to England (and therefore higher when home receipts are considered) that exceeded what cricketers would earn from the game until the Packer revolution.
Not that tours were unprofitable (at least to England) in the ACB-era. Players could expect around 50,000 in today's money for their six months on tour. It was the home salaries that lagged, and even a late increase (undercut by rising inflation) prior to World Series Cricket did little to bridge the gap between what they earnt, and what Packer was willing to pay.
Brettig picks up the story in 1979. Both Packer and the ACB were haemorrhaging money trying to compete for local interest, the ACB for lack of star players and control of their game, and Packer for lack of cost control. The untold story, until now, of Bradman and Packer agreeing to treat for a resolution puts these into perspective. Packer had no need to retain either the players nor overall control of cricket; his interests lay in selling the product and in Bradman he found an unlikely ally.
The stability of player incomes over almost 50 years was underpinned by the inherent conservatism of the Board. Its membership was driven by continuity. A certain amount of income was received from ticket sales, an amount allocated to associations and player expenses. Bradman didn't believe in full professionalism, but he did believe in attractive cricket and his later writings showed plenty of willingness to embrace innovation in the game. Unlike most of the board, paralysed by fury and disbelief, Bradman was pragmatic and readily acceded to Packer having not only the TV rights, but the marketing of the game via PBL in exchange for certainty and control.
The deal was a fleecing of the ACB, but it made sense for a Board entrenched in the amateur era. As Brettig describes the post-WSC period, it took almost a decade and a South African rebel for the ACB to realise that they were seeing a fraction of the money coming in to cricket. For players on the ACB books, renumeration was well above the pre-WSC era, but remained well below what it could have been.
There was a further issue with PBL having marketing control of the game, and that was their focus on ODI cricket as the core product of Nine's summer. Test matches and ODIs were interspersed throughout the 1980s and early 1990s with the tri-series competition given higher standing and better promotion. Lynton Taylor as Chairman of PBL marketing had no problems telling the ACB that Test cricket was dying. Average crowds declined through the 1980s as Australia struggled, and beyond before reaching a nadir in the early 1990s when the MCG was hosting as many days of ODIs as Test matches with three times the average crowds.
A change had been sweeping through the Australian Cricket Board though. Empowered by younger business oriented members in Malcolm Gray and Graham Halbish, the retirement of Colin Egar and Bradman (officially), and the success in hosting the 1992 World Cup the board took back control of selling their product.
The "revolution" in the management of Australian cricket, that started in 1977 with WSC, became a Board transition that didn't end until 1994 (if not later when it achieved independence from the State Associations). Whereas the Bradman-era Board was unwilling to treat with Packer, then blindsided by his ability and willingness to outbid them for players, the Board from the mid-90s on has been more frequently accused of being for players and product over administration. The players, empowered by the Board's growing income, unionised and ensured their contracts soon jumped far above the y-axis of graph shown above.
The rhythm of cricket changed too. Test cricket returned to the centre, and not unremarkably, soon recovered both crowds and prestige. The ODI tri-series carnival that drip fed cricket into lounge-rooms nightly for the entire summer went into a terminal decline, was progressively shortened, and finally replaced by domestic T20 cricket.
This book provides an important glimpse into these changes, the personalities involved and the downsides to Nine/PBL's control of many aspects of cricket in an era otherwise tinged with nostalgia and a belief that everything changed, when in some important aspects nothing changed at all, and in others the change was fundamental, but much more drawn out than supposed.
4th March, 2019 00:39:38
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ICC competition reform with Tim Cutler, Associate Cricket Podcast
The ICC's major reforms to associate playing competitions have been released and former Cricket Hong Kong CEO Tim Cutler (@timcutler) joins Andrew Nixon (@andrewnixon79) joins Russell Degnan (@idlesummers) to discuss that and various other issues. The World T20 sub-regional tournaments contineu and we look back at the Asia East (0:20) and Africa Southern tournaments (4:30) which had a few surprises and almost a major upset, and China and South Korea joined the growing list of teams with official women's T20 matches (8:20). We cover the ICC's new league structures in some detail looking at changes to 50 over, 4 day and 20 over cricket (9:20). The tail end of World Cricket League division three was in play as we recorded and we discuss some of the outcomes of that tournament (27:20) as well as the change in ICC streaming policy. We then turn to match fixing which has been a prominent issue in the past month with associate cricket continuing to encounter significant risks of corruption (42:30). There is news regarding the UAE T20x, the Asian Games, Kinrara Oval in Malaysia and the ICC women's development squad (54:00), and we conclude with previews the World T20 East-Asia Pacific group B and ACC West Zone tournaments (1:06:50).
Direct Download Running Time 69min. Music from Martin Solveig, "Big in Japan"
The associate cricket podcast is an attempt to expand coverage of associate tournaments by obtaining local knowledge of the relevant nations. If you have or intend to go to a tournament at associate level - men`s women`s, ICC, unaffiliated - then please get in touch in the comments or by email.
20th November, 2018 21:19:30
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Fixing the ICC ratings
In my post on the fundamental sameness of ratings I implied some criticism of the ICC ratings. Many choices about how to construct a ratings system are (for the most part) either a design choice - home advantage doesn't matter with a large sample and even schedule - or relate to what is trying to be achieved. The decay rate will be different if a rating is supposed to reflect the last 2 months versus the previous two years.
The ICC ratings go to a championship trophy and should therefore reflect the previous 12 months, but with scheduling so uneven that is near impossible, and different choices have been made to provide a relatively simple system.
As discussed in a previous post however, the ICC ratings have some genuine problems. The choice to cap the implied probability at 90% means that for a large number of matches the ratings are a poor reflection of the quality of the sides. Similarly, the choice of decay that reduces then drops previous results causes other issues when the quality of opposition has already been accounted for.
Both of these issues are relatively easy to fix, and this post discusses the benefits of doing so, particularly in a new world where nations with wildly different abilities must both be included in the ratings - as opposed to the full member oriented system where all teams were broadly at the same level.
Changing the implied probability
As noted, the basic issue with the ICC ratings' implied probability is that once teams are more than 40 ranking points apart the ratings assume that the stronger side will win 90% of matches. This pushes the ratings apart - particularly when one side is significantly weaker than their opponents. It also means that the points on offer for wins over strong sides are lower for bad sides than good ones - which limits the ability of the ratings to adapt to changes in ability.
As the graph above shows (the blue ICC lines), once the gap between teams gets above 40 points, their points gained relative to their current rating remain same. The value of a win therefore declines as the probability of them winning decreases. At its most extreme, when sides are rated more than 180 points apart, a strong side will get more points for losing a match than the weaker team will get for winnings it.
The solution is to adjust the points on offer in proportion to the ratings gap of the two teams, as per the red lines in the graph which eventually settle on the stronger side receiving no additional points (ie. their current rating) for a win - an implied probability of 100% - and the weaker team half the ratings gap plus 80 in the unlikely event they win.
The formulas would therefore be as follows:
|Ratings gap||ICC Formula||Proposed Formula|
| ||Stronger team||Weaker team||Stronger team||Weaker team|
|0-40||Win: OppRat + 50|
Loss: OppRat - 50
|Win: OppRat + 50|
Loss: OppRat - 50
|Win: OppRat + 50|
Loss: OppRat - 50
|Win: OppRat + 50|
Loss: OppRat - 50
|40-90||Win: OwnRat + 10|
Loss: OwnRat - 90
|Win: OwnRat + 10|
Loss: OwnRat - 90
|Win: 0.1 * OppRat + 0.9 * OwnRat + 14|
Loss: 0.6 * OppRat + 0.4 * OwnRat - 66
|Win: 0.6 * OppRat + 0.4 * OwnRat + 66|
Loss: 0.1 * OppRat + 0.9 * OwnRat - 14
|90-180||Win: OwnRat + 10|
Loss: OwnRat - 90
|Win: OwnRat + 10|
Loss: OwnRat - 90
|Win: 0.05 * OppRat + 0.95 * OwnRat + 9|
Loss: 0.55 * OppRat + 0.45 * OwnRat - 71
|Win: 0.55 * OppRat + 0.45 * OwnRat + 71|
Loss: 0.05 * OppRat + 0.95 * OwnRat - 9
|180 plus||Win: OwnRat + 10|
Loss: OwnRat - 90
|Win: OwnRat + 10|
Loss: OwnRat - 90
Loss: 0.5 * OppRat + 0.5 * OwnRat - 80
|Win: 0.5 * OppRat + 0.5 * OwnRat + 80|
They look more complicated than they are. The existing ICC ratings use either a team's own rating or the opposition. The combination allows the much more gradual increase in points shown above (optimally the area between 0 and 40 would also be curved, but I have chosen to leave it as is).
The changed implied probability shows the benefits of this approach:
Whereas previously teams were either closely matched or a 90% chance of victory, now their approximate chance of victory can be determined across a full range of ratings gaps.
This change would only make subtle changes to the ratings. Bangladesh's improvement a few years ago would have given them a more rapid (and noticeable) boost, reflecting their actual ability rather than their long period of tepid performances. The odd associate upset would have been better reflected in their ratings - when they are included. But as these results are rare, the broader outline of the ratings would be the same. The more important change is to the decay rate.
Changing the decay rate
As a matter of basic maths, if points were to accumulate indefinitely then new matches will have a decreasing effect on the ratings. The ICC works around this in the simplest way - by reducing the previous two years by 50% and excluding anything before that. But it has an unfortunate side effect: each exclusion date, ratings jump, sometimes substantially, and often, in strange directions.
The effect of this change can be seen in a simple example. Here a team plays (and wins or loses matches) at different levels over the course of several years. The true rating of the team in each year (and which, nominally the ratings should reflect) is as follows: 100, 80, 100, 120, 120, 120, 100. The graph shows this shift (at the start of the year) and the impact of the ICC decay formula (at the end of each year).
Notice that, because the previous year is reduced to 50% in preparation for a new year, the rating shifts away from the true rating at the end of the second and third years as old results are re-weighted up relative to the past year. The ICC rating eventually meets the true rating only if the team has maintained the same rating for two years, otherwise it is often substantially far from correct.
The oddity with the simple choice of decay is that it is also unnecessary. The "natural" way to ensure old results do not impact the rating without unseemly jumps is to merely divide both the points accumulated and the number of matches by an amount. In the graph above this was 3, effectively reducing the impact of old results by a third each year (and by a ninth the following year).
The proposed system never quite matches the yellow line - though arguably nor should it - but it is consistently closer than the ICC and gradually gets closer the longer a team stays at the same level (in the third year of ratings at 120 it reaches 119).
More importantly, there are no jumps. As both points and weights are declined by the same amount, a team stays on the same rating until they play. Which is exactly how it should be.
23rd October, 2018 23:33:04
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The fundamental sameness of ratings
Two things generally hold for any half-way reputable ratings system:
- Some observers will criticise a particular ranking because they've forgotten a set of results occurred.
- The basic result will look the same as everybody elses. The good teams will be good, the bad teams will be bad and there will be a big blob in the middle.
It is hard to fuck up a ratings system.
People do. But since in its most basic format, a league table is a ratings system, and a league table will usually give a decent approximation of the best and worst teams, it is quite hard to do worse.
It is worth considering its constituent elements though, for anyone planning to construct one, to outline the basic issues of design, and problems in scheduling structures that bring them undone (or need to be corrected for). To do this I'll look at five systems: a basic league table (which as noted, is a form of rating), the ICC system for cricket, the IRB system for rugby, Elo (which is widely used, but I'll focus on football) and my own cricket ratings.
Margin of victory
Your standard results-based backward-looking rating system (there may be others but they aren't widely used) bring together a set of results and project the quality (and possibly future performance) of teams based on games played. There are two basic two options for the result: the result; or the margin of victory.
A league table and the ICC use just the result. The IRB has a little each way by providing a bonus for a larger margin of victory, while the Elo soccer rating and my own cricket ratings use the margin of victory. The benefit of using the margin is that it provides more information, particularly in sports where the result is relatively predictable but it might reasonably be considered that there is a Pythagorean relationship between the points differential and eventual wins.
One thing I have considered but not implemented was to account for Test draws by examining "distance to victory". Hence a drawn match with one side 100 runs in arrears and the other needing 2 wickets would have a margin of 100 - 2 wickets (nominally 50 runs in my ratings). A non-linear relationship for wickets is another margin option to consider. Note that the added accuracy of these changes is marginal at best.
Strength of opposition
Here lies the first leap forward from a basic league table: the measuring of schedules. In many leagues this is not strictly necessary as the schedules are relatively even. In cricket it is nonsense to forgo it.
Accounting for opposition means having an implied probability of victory. That is: if an average team (50% probability of winning against an average team) is expected to win less than half of the matches against their schedule, then the points awarded are increased to make up the deficit. All ratings have an implied probability of victory, but the results vary.
My ratings are margin based - though there are adjustments for wins/draws - and use a "normal" implied probability around a standard deviation of 180 runs. Basic Elo ratings are based on three results (win/loss/draw) and therefore use a different function. Both of these are smooth curves, as per the image.
The ICC and IRB use linear models. The downside to linear models is that eventually teams hit a limit of 0% or 100% probability of victory, in which case their rating cannot increase (or decrease) in proportion to their ability versus their peers. For the IRB, this caps the maximum rating difference at 10 points (100% likely to win) - bonuses have got New Zealand up this limit, but the only way is down.
The ICC does something quite strange - on which more details can be found in this older post - which is to cut the implied probability at 90%. Teams above this threshold can theoretically keep increasing their rating to infinity, and vice versa (which is why a number of teams have been marooned around zero. There are ways this could be fixed, but will be the subject of a later post.
Strength at home
Adjustments to the implied probability are often made for home advantage. This is not strictly necessary as the difference is marginal, but if a schedule is sufficiently unbalanced it can be necessary.
A league table (needless to say) doesn't do so, and nor does the ICC. The other systems being examined do and the implied increase in probability given a ratings gap is shown above. Note that the IRB is linear as it merely shifts the system by 3 points. For Elo and my own ratings the greatest increase in probability is in the centre (around 50%) as that is where the variability is highest. A 1% probability of victory doesn't tend to shift regardless of home advantage.
Some systems extend this further by having a "home" and "away" rating that allows variation in the quality of home field advantage. The upside to this is that some teams are substantially better at home (teams at altitude for example) or poor away (isolated teams needing to travel) and this allows that to be accounted for. The downside is that it halves the amount of data - which for cricket is already sparse - unless some combination of recent home and away results is made. The standard method of adjusting for home advantage as if it is always the same isn't perfect but no rating system is. There are always trade-offs and the biggest is yet to come.
Recency of results
The fundamental difference between most systems is the speed and method by which they exclude results. Prediction models generally show that the more data put in the more closely the predictions run, which would imply that recent results should decay very slowly. However, no team stays the same, personnel changes, improves and declines, there is an element of form (perhaps indistinguishable with luck) and injuries will subtract and then add to quality just as the rating adjusts. There is no right answer.
Seasons offer a simple method, and a league table that resets to zero is as good a method as any if you don't want to predict results during the season. Conversely, it is a complex and unknown question how to adjust ratings from the previous season. FiveThirtyEight's Elo models converge to the mean, producing strange zig-zags for persistently strong sides. Leaving the rating as the previous season is not any better though. The most promising method if seasonal boundaries are fixed is to substantially lower the weight of old results, such that new results drive fast change, then get embedded in.
My ratings had a series of more complex issues to solve, and therefore decay in strange ways. Firstly, historically some teams played relatively infrequently - South Africa in the 1960s being the canonical example - which meant that when their ability moved, a differential system (as used by Elo or the IRB) would shift the teams with well-known ratings just as much as the team with few results. The first change was to add a weighted shift for number of results.
Secondly, the sparseness of matches and clumped schedule where teams would play the same side five times in a row means that there times when a rating needed to either shift rapidly or return to a spot after one bad (or good) tour. The solution was to keep a "form" variable that would add to the change if the direction of change was aligned. The "decay" of my ratings is therefore not a straight line, but an area: the top-line being relatively slow, and the bottom relatively quick, but converging after a couple of years.
As noted previously, the ICC ratings make strange and unnecessary choices regarding their result recency and every year the shift in ratings when no games have been played makes that clear. That aside though, the choice of decay is driven largely by the number of matches being played (and therefore the amount of data) and a personal preference for monitoring form. There is no correct answer, as even if the aim was to predict future results, there is unlikely to be a high level of consistency from one year to the next between models.
The final element to ratings is actually the most complex element of all. For many leagues, where continuity is taken for granted, a baseline only matters as a point of historical interest. For others, such as the Elo chess ratings, where the volume of participants entering and leaving is high, there can be an impact on inflation, but not relative ability.
Cricket, and to an extent football, have their issues with baselining though, and it is worth considering them. Firstly, the introduction of new participants into a small closed system (like full member cricket) means adding a team at a level below the others that may (at some future point) be level with them. I rebaselined my ratings to 1000 for each of the first ten full members (using first-class ratings for Ireland and Afghanistan), and took their first rating as the lowest current member.
This is definitely wrong, as seen by the sharp drop in the rating of Bangladesh on entry to Test Cricket. The alternative is to run a new entry forward until they settle and then add them. But because of the accelerated decay detailed above, the wait for Bangladesh to find their level was short.
The second issue is more complex, and more likely to matter in other sports. In cricket, most teams don't play each other. To a degree even the full members don't play each other, but the standard rating system works by transivity: A > B and B > C means A > C. As long as a subset of teams play a random number of teams in the overall set of teams a rating system will work.
But this doesn't always happen. In cricket the full members play, and the associate members play (also split into tiers and regions), and on rare occasions there is a small set of matches between subsets of each of those sets.
Thus while the relative strength of each column of teams within a "league" is set, there are rarely enough games between teams in other leagues to be able to baseline the leagues against each other. In the diagram above each tier could be shifted up or down relative to the others, as only one or two teams is playing in each. Recently (and finally) the ICC extended their rating system to all Women's T20 International teams. it is a welcome change but some teams (such as Argentina) have not played outside their region for some years, while others (such as PNG) play a handful of matches outside their region every few years. If EAP was to improve, then PNG (as their only representative) will gain points internationally, then lose them to their regional rivals. The imbalance will change, but slowly, as PNG shuffle points back and forwards like fetching water from a well.
Football suffers a similar issue with relatively few inter-regional tournaments (like the World Cup) internationally or (the Champions League) domestically. Any ranking system that combines different subsets should be approached warily, though a correction is nearly impossible to provide.
The solution, probably, is to provide a regional subset adjustment system, whereby teams are weighted by their games within each subset and the whole subset shifted as the ranking of any member in the set changes. This would maintain the relative distance between all teams using the information we know - the relative rank of each team in their subset and the relative results of a representative team in the subset against a representative of another subset - and adjust the information we don't - the relative rank of each team in the whole set. Unfortunately, in Test cricket, the total number of matches between Test and Associate subsets is two and the Associate subset wasn't too well known anyway.
For the ICC, the benefits of a global ranking system will outweigh the complaints from the small handful of people following cricket in the Associates closely enough to notice oddities in the rankings. And if you do want to complain, remember, ratings systems make a lot of choices, and in most cases it isn't clear which are better - though I obviously have my opinion.
And anyway, they are all much the same. It is hard to fuck up a ratings system.
14th October, 2018 22:16:14
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