I think I read that Jimmy the Greek got fired from his sports job for saying that blacks dominate American sports because they have more talent. It's probably more complicated than that but the science of human genetic differences is controversial mainly because of its potential implications for the subject of racial differences. What with White Supremacists and Nazis making a comeback, it's hardly possible to dispassionately discuss such matters.
The standard line on the left, I think, is that race is a social construct. Well, of course, but that doesn't mean that it isn't related to biological history. I think that the left - and I'm slightly left myself - overplays its hand when it insists that noticing differences correlated with race is evidence of racism or other dastardly crimes against propriety. If you publicly insist on a claim that anyone can see is false you discredit yourself more than anyone else.
I would guess that anyone who follows sports in America knows that despite whites being far more numerous in the country than blacks, most NBA teams are much more black than white. So are college teams. And nearly all the superstars are either black or mixed race identifying as black. In track, nearly all the top sprinters have some combination of West African and White ancestry, while the marathon is dominated by East Africans from Ethiopia, Kenya, and a few other countries. NFL Football is more complicated, with cornerbacks being nearly all black, wide receivers and defensive ends being mostly black, while offensive guards, centers and quarterbacks are majority white.
These differences have a lot to do with physical characteristics, especially size, strength, and speed. There are plausible evolutionary reasons why systematic differences might exist, one of the most obvious being that Europeans had to adapt to living in a cold climate. So when the modern human ancestors of Europeans moved from Africa to cold country, they experienced evolutionary pressures to develop blockier bodies, just like other animals living in cold climates. This could have happened partly due to loss of long limbed genes and partly due to interbreeding with Neandertals, who had been living in the cold climate for half a million years.
Other things being equal, being able to run fast and jump high are pretty useful, but a blockier body prevents that. Ergo, an evolutionary explanation for why White Men Can't Jump - it was cold. Speed is a factor for every position in the NFL except kicker, so blacks are overrepresented compared to their percentage in the population at every other position. Whites are relatively highly represented at quarterback and center, positions with less of a premium on speed. This article has the racial breakdown of every NFL position. Whites are a majority at only four non-kicker positions.
The average African-American has about 17% European genes, mainly, but obviously not exclusively, a legacy of slavery. It would be interesting to know how the genetics break down at the various positions.