First of all, in racial terms, the game has become so black American and internationally dominated that the typical white American fan has nobody special to root for. That's not racism, but it is racial. And it's not a problem. If a Native American ever makes it into the NBA, he will instantly become my favorite player because I will racially, culturally, and physically identify with him. I understand and completely accept why so many white guys love Larry Bird, just as I understand why there are 1,000 black kids in Kobe Bryant jerseys at every Laker game played here in Seattle. It's a tribal thing.
But the racial aspects of fandom can easily become racist. And I think that many white fans, having no player like Larry Bird or even Tom Chambers to root for, have consciously and/or subconsiously turned that lack of a special white player into an indictment of the league in general. And since the league is black it becomes an indictment of blackness.