what you dont seem to realize is to make it to the highest level of any sport you have to be gifted athletically, but also very competitive individual.
thats a difference between nba/nfl journeyman n an allstar.
all the top nba/nfl players are also the most competitive ppl in the world. their desire to win > other individuals. your division 1 wrestler or bjj black belt simply doesnt have mental fortitude to keep up with these guys. he will simply break when overwhelmed with their athleticism + mental toughness.
on top of that most of these guys grew up in the hood, so you can be sure they have a mindset of a fighter. they literally grew up fighting.