The Diving Champions of the (Football) World

Aside from early losses by Germany and Spain, the biggest surprise of the World Cup so far is probably the inability of Italy (the reigning champions) to win either of their first two games. First they drew with Paraguay, ranked 31st in the world, and then again today against 78th ranked New Zealand.

In both cases the Italians came back from a goal behind, and in the latter game did so on the basis of a dubious penalty. De Rossi's spectacular dive after getting his shirt gently tugged by Smith was a wonder to behold, revealing yet again that the Italians are undisputed masters of the simulated foul. Even the Wikipedia entry on the art of diving acknowledges this:

Diving (or simulation - the term used by FIFA) in the context of association football is an attempt by a player to gain an unfair advantage by diving to the ground and possibly feigning an injury, to appear as if a foul has been committed. Dives are often used to exaggerate the amount of contact present in a challenge. Deciding on whether a player has dived is very subjective, and one of the most controversial aspects of football discussion. Players do this so they can receive free kicks or penalty kicks, which can provide scoring opportunities, or so the opposing player receives a yellow or red card, giving their own team an advantage. The Italian national football team have been well known to use this tactic... In fact, their victory at the 2006 FIFA World Cup has been overshadowed by the sheer volume of controversial dives.

While the anecdotal (and video) evidence against Italy is strong, it would be useful to have a statistical measure of diving on the basis of which international comparisons could be made. One possibility is to use data on fouls suffered. For instance, in the latest game, Italy was fouled 23 times while New Zealand suffered just 10 fouls. Either New Zealand is an unusually aggressive (or clumsy) team, or a number of the "fouls" suffered by Italy were simulated.

Since data on fouls committed and suffered is readily available for all World Cup games, it should be possible to sort all this out statistically. Suppose that in any game, the total number of fouls suffered by a team depends on three factors: its propensity to dive (without detection), the opponent's propensity to foul, and idiosyncratic factors independent of the identity of the teams. Then, with a rich enough data set, it should be possible to identify the diving propensity of each team. There are subtleties that could confound the analysis, but a good forensic statistician should be able to handle these. Perhaps Nate Silver will take up the challenge?

In the meantime, for a lesson on how not to dive, enjoy this legendary "posthumous" effort by Gilardino in a 2007 game between AC Milan and Celtic: