If it's OKAY to say that certain races/ethnicities are superior in athletic endeavors (observe the dominant race in the NBA, for example) why is it forbidden to say that certain races/ethncities are superior in academic or intelligence endeavors?
Because if you say that, the inescapable conclusion is that other races or ethnicities are correspondingly inferior to the superior ones...and that conclusion, of racial inferiority, will get you labeled a racist Nazi Klansman bigot eugenicist faster than you can say "Margaret Sanger."
It is not OK to say this. The PC crowd attributes this skill to poverty (other sports require expensive equipment and facilities). Bball requires only a ball and a hoop nailed to a wall somewhere in the alley is their explanation.