Is because it's directly tied to the fact there are more black athletes in pro sports? The white guys probably love the game just as much, maybe more since they may have had to worker harder to overcome their lack of athleticism to be able to compete. But at the highest levels of pro sports it takes every bit of that plus the eye popping measurables too. So since many white guys get passed over in the pro drafts they get an early jump on the coaching ranks.
I recognize there is still plenty of racism and prejudice in this country. I just don't think it's as prevalent in such high dollar high/risk jobs as some of the race-baiters would have us think. It costs big bucks not to hire the best candidate when potentially hundreds of millions of dollars are at stake.