In this post I consider the relationship between World Cup squad concentration, insofar as investigating the countries where squad members play club football in, and international performance at the competition.
Do more diverse squads perform better at the finals? The argument could be that squads made up of players that hold professional contracts in different leagues, that have different playing styles, create a stronger collective. Maybe diversity creates some type of intangible effect which establishes a stronger whole?
Maybe the logic can flow the opposite direction too – more concentrated international squads, where most of the squad play in one league have a better understanding of teammate abilities and can create a more consistent style. This could form a more coherent unit?
I’ve looked at the data for the 2014 World Cup, calculating HHI’s for the 32 squads but neither argument seems to hold water. Excluding Russia who are outliers in that 100% of the squad were sourced from Russian Clubs, the more (less) diverse teams do not perform significantly better or worse.
Croatia displayed the most balanced diversity in that they sourced an evenly low number of players from a wide variety of different leagues but exited at the group stage. The next most diverse, Algeria and Uruguay both exited at the last 16.
The most concentrated teams such as England and Mexico exited at the group and last 16 stage respectively. The eventual winners Germany were the third most concentrated team – the Germans only sourced players from 4 countries. Lots of the other relatively concentrated teams still exited at the group stages of the finals such as Italy, Honduras and Iran.
When it comes to the Finals, maybe it just doesn’t matter whether international squads are primarily made up from one country or many.