I dont know what you mean about size, whether its length or girth, oh sorry height or weight but i do know that football has gone from where it was more of a touch game and finese to now sheer athleticism and power.
You get a case scenario of where players like Gerrard, Essien and the like are wanted for 30m plus while touch players like Pizzarro are wanted for so much less
Players like Zizou are so hard to find while we extol the virtues of Adriano, Henry, Sheva,Emerson and these kind of players
I guess its also to do with coaches who want more physical kind of players, thank goodness for the likes of Ancelotti and Rikjard