The proportion of skill to physical aptitude needed to be successful in soccer is much higher than in any other sport. Bottom line: you can be a 5-foot meatball like Maradona, but still be one of the greatest players of all time as long as you got the skills. That's much different than American sports, where if you are not of certain height/mass, you just can't play the sport at the highest level. It is just the way the sports are played, they require different sets of attributes.