Wednesday, July 13, 2011

Tall = Good? Taller = Better? Height and Football

It wasn't all that long ago when playing midfield seemed to require more height than ever to crowd the center of the pitch. As a matter of fact, the average height of professional footballers has been increasing for a number of years now. The latest Professional Football Players Observatory report of the demographics of footballers in Europe reveals that players in the Czech Republic, Germany, and Denmark on average are around 1.83m tall - that's slightly over 6ft - while even players in "shorter" countries like Spain and France average slightly less than 5'11", as the following graph from the report shows. Mind you, each of these averages is significantly taller than the average male in these countries.

(c) 2011 Professional Football Players Observatory

In stark contrast, FC Barcelona seems to defy these general trends in professional football. While Iniesta, Xavi, and Messi are footballing giants, much has been made of the fact that Barcelona's midfield is one of the shortest around. What is more, they can probably look most guys in the Barca dressing room in the eyes. In the same report I cited above, Barcelona take the honors for shortest club in all of Europe (in terms of average height) at 177.38m - that's less than 5'10". So now, the latest fad seems to be what Germans like to call "Stehaufmaennchen" - or roly poly doll - a player whose center of gravity is low to the ground. 

So what's better? Tall or short?

I won't pretend to have an answer; but I did find a little bit of data to play with, courtesy of Achim Kemmerling of the Central European University in Budapest. Achim shared with me a couple of fun graphs that connect average population height (for men and women separately) and FIFA coefficients (some countries appear several times because several body height samples exist for this country). So here is average male height and FIFA coefficient first, along with a regression line. Countries that lie above the line play better football than their height would lead us to predict; countries below the line play worse than their height would predict.

To me, this tells a pretty powerful story; tall is good, and taller is generally better. The correlation is a robust .53. But: there are some notable outliers, amongst them most obviously Spain, which lies way above the trend line. So players in Spain are significantly shorter than their FIFA coefficient would suggest. Put the other way around, Spain's football players perform much better than their height would suggest. Interestingly, there are two other countries that outperform their male height: the Netherlands and Germany. What do these countries have in common? Well, they obviously placed 1, 2, and 3 at the most recent World Cup!

Does the same hold true for women? The next graph suggests that it does.

The correlation is positive, too, but less strong at .36. While the outliers aren't as clear here as for the men, we see a similar pattern. All the top teams in this year's World Cup are located above the trend line.

As Achim told me, these patterns are robust, even when we account for things like a country's wealth or population size - typically good predictors of success in international football competitions. But it's important to keep in mind that these numbers are for national teams, of course, and therefore not directly comparable to the professional footballers data.

In any case, so what do we make of this? For starters, taller does seem to be better - that's what the data clearly show - but only up to a point. Some countries - the best footballing countries - manage to exceed their predicted performance (based on height) on the pitch. Only question is: should we assume this over-performance to last - have they found the secret for overcoming the physical laws of football - or will these countries eventually regress back to the mean? Without data collected over time, this is impossible to say. What we can say is that size matters, as one might expect, but there's clearly more to putting the ball in the back of the net than towering over your opponent.