The NFL Network replayed Super Bowl III on Saturday and I watched some of it. That was the one in which Joe Namath and the Jets upset the Colts in what is still one of the biggest upsets in sports history, maybe the biggest.
That game took place in January of 1969. The NFL had been integrated by then for a number of years with the NFL (and AFL)being about a third black. Both the Jets and Colts had a number of starting black players, but whites were still well represented at the "skill" positions and on defense. The Colts used mostly whites to run the ball, while the Jets started two white wide receivers and the Colts one. Both teams had white defensive backs, including cornerbacks.
The NFL at some point had a pretty good equillibrium, as far as fairness toward both black and white players, before thepermanent Cultural Revolution began to deify the black athlete. Part of the deification process was to inculcate the policy and supporting belief system that only blacks are good enough to play most football positions.
No one knows for sure what the exact racial makeup of a "colorblind" NFL (and college I-A) would be, but my guess would be that it probably came closest in the past in the mid-1960s, after the integration process had been well under way but before the Cultural Revolution came into full blossom in the late '60s -- about a quarter black and three-fourths white, similar to baseball when it was popular with blacks. Tailback should be the blackest position, but whites should easily be at least a third there, and maybe half. There are plenty of whites who would be very good power backs, and there is no shortage of smaller ones who are fast, smart and shifty.
An NFL that is a quarter black would still be significantly over-represented by blacks given their proportion of the population of about one-eighth, but would be realisticgiven blacks' athletic ability and interest in football. Could be more than a quarter, could be a lot less, but one thing for sure is that today's unbending Caste System rules have created an almost entirely artificial racial construct.