Stat Attack

Published in Hoops Scene (Shamrock Rovers v Drogheda United, 20 May 2011)

“Figures often beguile me, particularly when I have the arranging of them myself; in which case the remark attributed to Disraeli would often apply with justice and force: ‘There are three kinds of lies: lies, damned lies, and statistics’.” Mark Twain

If you go down to the bookshop today, you may be in for a mild surprise. As amongst some of the terrible sports autobiographies, sports almanacs and books on fishing, you will find a number of books that use statistics to explain how teams win and that debunk a number of sporting myths. It seems the sports economists and statisticians have gone slightly mainstream.

A classic of this field is Michael Lewis’ bestseller Moneyball. Lewis is the American financial journalist who wrote Liar’s Poker about his time as a Wall Street trader and that withering report on Ireland’s economic situation for Vanity Fair last March (When Irish Eyes Are Crying). However, the must read for sports fans is his book telling the true story of how Billy Beane, the general manager of the Oakland A’s, turned his team into a force in America’s Major League Baseball despite the mediocre finances available to them. How did he do this? Well, his key weapon was ‘sabermatrics’ or baseball statistics. He used statistics to rubbish common held baseball beliefs on topics like stolen bases and runs batted in. It was in the transfer department that Beane excelled, using these stats to find undervalued players who he then signed for the A’s making his squad compete with such financial and sporting heavy hitters like the New York Yankees. This story is set for a Hollywood version with Brad Pitt staring as Beane in a script by Aaron Sorkin. The use of sabermetrics has now become commonplace in baseball with the Boston Red Sox being a leading exponent. The Red Sox owner, John Henry, has looked to bring some elements of sabermetrics to the ‘soccer’ team he owns, Liverpool football club.

With baseball there is a defined set out outcomes with each element of play. Essentially it comes down to a battle between two players; the pitcher and the batter and between strikes and balls. Each element of the play can be assigned a set of outcomes. The same cannot be said for football. It is 11 players versus 11 players but it is in a very fluid format. So can footballmetrics be used to the same extent as baseball’s sabermetrics? Simon Kuper, Financial Times sports journalist, teamed up with Stefan Szymanksi, a sports economist, in 2009 to publish Soccernomics which threw a cold analytical eye on football and explained Why England Lose and other curious football phenomena (as the book was titled in the UK). Like in Moneyball, Soccernomics sets out challenges to many of the perceived wisdoms of the sport using data collated by statisticians, football nerds and even FIFA to reveal more about the game. The chapter ‘The Economist’s Fear of the Penalty Kick’ should be required reading for any football fan and maybe everyone at Shamrock Rovers given our recent history with the penalty kick.

The authors recount the story of how having access to a database of 13,000 penalty kick outcomes helped Germany defeat Argentina in the 2006 World Cup quarter final and how another database should have helped Chelsea win the Champions League in 2008 but for Nicolas Anelka to go against the plan in the shootout in Moscow letting Manchester United win. As most footballers have a dominant kicking foot, by kicking to that side they strike the ball cleaner and hence have a greater chance of scoring. However, goalkeepers know this or they may have access to some penalty statistics on their opponents. The best penalty takers in world football mix it up, making the goalkeeper guess.

In Soccernomics, the statistic database developed by Basque economist Ignacio Hertan was used to recommend the right approach. His database, with nearly 1,500 penalties from the late 1990s, recommends penalty takers to shoot 61.5% to their dominant side to maximize their chance of scoring. The keepers best strategy for saving was to dive to the kickers dominant side 58%. A similar exercise was done looking at 500 penalty kicks from La Liga and Serie A. 57% was the answer in the paper produced on the subject by Steve Levitt who is also one the authors of theinternational bestselling book on economic theory Freakonomics.

This year another book has emerged to challenge a few more sporting norms. Scorecasting: The Hidden Influences behind how sports are played and games are won tackled such topics as are stars more valuable in a team than a balanced team and why is playing at home so valuable? The authors, one a University of Chicago finance professor and another a writer for Sports Illustrated, answered the question as to how much is home field advantage worth to a team? Well, on average teams at home will win around 60% of their games and that statistic is similar across games such as baseball, cricket and rugby as well as football. The stats for various competitions are Major League Baseball 54%, American Football 58%, International Rugby 58%, International Cricket 60%, England’s Premier League 63%, South American football 65%, La Liga 65% and Serie A 67%.

But what is the reason for this? Is it the difficulty for teams in travelling away, or that the home team is more comfortable in the familiar surroundings in the stadium? No, the answer rests with the match officials and the influence of the crowd.

Many refereeing decisions are subjective and are influenced by players and the crowd reaction. So what is not under the players influence? Well, the number of minutes added for injury time at the end of a game. A London School of Economics Professor carried out a study on the length of added time in over 750 La Liga matches. They determined that in tight games with the home team winning by one goal the injury time is on average two minutes. However, if they are losing by a goal the average injury time is double that, at four minutes. If the game is a draw, the average injury time is three minutes. If the team is well ahead or behind where adding or reducing time won’t make any material difference, the average injury time remains at three minutes. Similar injury time bias towards the home team have been found in the Premier League, Serie A and the Bundesliga. More bias towards the home team, backed up statistics, is that the home team receives fewer red and yellow cards than the visiting team. The size of the crowd also has an influence with larger attendances leading to a larger bias in favour of the home team.

Looking at these statistics, it seems the referee is helping the home team, prolonging the game to help them score in a tight game, reducing the time if they are winning by a small margin or giving them less yellow or red cards But why? Is it the influence of the crowd makes the referee favour the home team? The answer seems to be yes. The referee knows that if they book or send off a home player then they will be subjected to a negative reaction by the crowd. So does the crowd reaction subjectively influence them and how can this influence be checked? A study in Sweden looked at 21 matches played behind closed doors. Without the influence of the crowd, the normal home field advantage seen in the statistics reduce significantly. Fouls given against them declined 23%, yellow cards 26% and red cards 70%.

Nobody is suggesting that there is a deliberate up front bias for the home team but the subtle pressure of the crowd unconsciously seems to influence the match officials. Statistics certainly seem to back up the view that the crowd influences the referee and hence the outcome of a game. For Shamrock Rovers, home advantage is just as important as any other team but maybe more so when viewed with the fact the Hoops essentially played away from home in every game from 1987 to 2008. Obviously the assembly of the superb squad by Michael O’Neill has been the major influence in Shamrock Rovers finishing runners up and league champions in the last two seasons. But we can also say that the large crowds that have turned up to support Shamrock Rovers in Tallaght have been influential in the Hoops’ recent success and that the statistics back that up!

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