Several questions I'd like answered:
Was there a shift from academia to sports as a means to escape poverty within the black community?
If so, when and why?
Prior to sports desegregating, was this trend also prevalent in Negro-leagues? i.e. Focus was put more on playing baseball/football/basketball than doing better in school
Given the 20 year rule. How has this affected the black community as a whole in terms of the education gap?
I don't buy the claim that sports are the "primary" means of class mobility for black people. For example, NBA players are more likely to be middle class than poor. To become a professional athlete, you need to have a lot of resources. I'd like to see any sources claiming otherwise.
Do you have any sources for athleticism being the predominant means for rising out of poverty? That seems unlikely given the resources required for most athletic pursuits.
FYI, you might consider x-posting this to /r/AskSocialScience; this question may be more up their street