Football is a different case from other college sports for one main reason: physical development. Your average NFL squad has players that are much bigger and st

Football is a different case from other college sports for one main reason: physical development. Your average NFL squad has players that are much bigger and stronger at every position. A receiver who is 5'9" has a fighting chance to be successful in many college conferences where there aren't monstrous cornerbacks but absolutely no shot in the NFL where size is a requirement. Undersized and underdeveloped players also risk significant injury by going pro too soon. College players need at least a year or two to build up the physical condition to compete at the next level. This is the reason why the worst NFL team would easily crush the best college team. The college team just wouldn't be able to handle the size of your average NFL squad.