When it comes to evaluating player performance, we have currently only scratched the surface. The amount of individual player data that is becoming available is but a snapshot of that player's true, core ability. So we have to deal with issue of sample size, along with the need to measure what is truly important in producing team wins on the pitch.
One of the most obvious indicators of a player's worth has nothing to do with his skill set. It's his age. Football demands a mixture of physical ability and various skills and in this guest post, I look at how the decline in the former leads to older players gradually, then dramatically disappearing from the Premiership scene (except for goalkeepers!).