there is one reason and one reason only
because in sports the main worker needs to be visible and recognized (and these days recognizable even) in order to generate a genuine product and therefore the most possible revenue, which forces the "playing field" to be somewhat level
if their visibility and direct association with the work product were not necessary to the collection of maximum revenue, then all the credit would have gone to some other non-black entity
ask yourself why do you celebrate George Washington or some other "forefather" as builders of this country
black people and other minorities built this country , and black people primarily built this country.
so ask yourself why you are not asking yourself, "How come black people are such good country and empire builders?"
go look and everywhere you will see credit taken from black people wherever their visibility is not, or their former presence and accomplishments are falsifiable or deniable and is no longer necessary for the generation of revenue or usage of produced commodities
if the playing field was level in this fashion everywhere-meaning you HAD TO BE SEEN for the success of the enterprise and your work product could not be divorced from you, or stolen or attributed to someone else- then you would be asking why are black people such great scientists, why are we such amazing researchers, doctors, lawyers etc...anything you can imagine we would be visibly seen as amazing at.
Just wait til genetic engineering catches up and athletes can be grown in the lab, there will be this intermediate period, before we comprehend the absurdity of it all and complications of the nascent biotechnology become evident, that you are going to be blown away by the sudden preponderance and dominance of freakish non-black and white athletes. (which is one of a million reasons why I am such an advocate of blacks studying the sciences en masse)
You want primary evidence look at the lack of commensuration between the number of black head coaches to that of black players and black position coaches. You don't need to SEE the black position coaches do their damn thing to generate revenue so their work product can be sublimated to a white head coach. Sheeeeeiittttttt how long has the NFL been holding out on letting black QB's do their thing by sublimating the work product of black position players through the mythical white QB and head coach? I can go on all day. Do you even comprehend how much psychological mindfukk (beyond the institutional cockblocking) has gone into holding back black people in the US from just expressing how awesome they are? you think you do, but you don't.... this shyt will go down into legends. maaaaaane let me stop here and get something don for the day, peace!
you want secondary, if not weaker or in more need of inference, evidence of what I am saying look at college football and all the shenanigans involved in actually keeping revenue out of the hands of the athletes, notice what happened with EA? notice that they are starting to remove names from Jerseys? notice that this year only the coaches are doing ESPN interviews, giving the athletes a lower profile? there is a proxy/surrogate visibility of the academic institution and its coaches as the actual attraction being perpetrated, in order to discredit the player's work product as the force behind the success of the sport.