Many of the fastest Whites switch to baseball, lacrosse, and other sports. And the ones who stick to football are systematically slotted to the racially appropriate positions in high school and earlier, and then denied scholarships at the major college programs, which serve as the NFL's minor leagues. And then many more are snubbed by the Combine, including a lot of fast players at the small schools.
It's more complicated than that of course, but how many black burners (4.39 or faster) were there out of the total number of black RBs, WRs, safeties and cornerbacks at this year's Combine? It was a small percentage. The Olympics up until 1984 or so showed that Whites could compete very well in the sprints, and some still do. If the Caste System were reversed and it was Whites nurtured along and given the great bulk of the opportunities, there would be more White burners at events like the Combine. But like so much else in this society, results are artificially brought about. If one just watched televised football and basketball, along with commercials and network programming in general, one would be convinced that the U.S. is a black majority country and that there are nearly as many Asians as Whites. The (fake news) media is pushing an agenda, one that appears cartoonish and primitive to those with eyes to see, but the great bulk of the White population is indoctrinated into it to a frightening degree and are seemingly impervious to racial realism.