Meh. What you really mean is that racism is still part of American and especially Boston culture, and no one doubts that. I seriously doubt, however, that the average Sox fan at games in Fenway has a problem with Betts, Bradley, or Young. Some of the animus toward Crawford was because he was overpaid and underperforming--exactly the same situation with Ellsbury and the Yankees right now or for that matter Sandoval with the Sox.
As I said in my earlier post, I think there can be no question that Boston fans overall have embraced this team--as they did the one in 2013--whose most iconic player is very dark skinned.
The thesis advanced in the OP, however, is that MLB is not only white, but intentionally and deliberately white, and with that I vehemently disagree. I think there are only so many great black athletes and that over time they have mostly gravitated toward football and basketball--sports they pretty much dominate despite being about 15% of our population--because the payoff comes earlier and is often greater. It is no coincidence that the richest athlete in America is Michael Jordan. And, speaking of skin color, a big chunk of his earnings came from that huge contract with Nike, and they ain't paying him because of affirmative actions. Nosiree. Jordan's name and face and personality and basketball skills sell a whole lot of shoes for Nike.