In his ponderous piece for Bleacher Report, writer Jeff Pearlman shares a few theories about why people hate Tom Brady. (Do people really hate the Patriots QB?) One idea relates to Boston’s reputation for being unfriendly to black athletes. Pearlman points out that the Red Sox were the last Major League Baseball team to have a black player — 12 years after Jackie Robinson joined the Brooklyn Dodgers. He then quotes Amy Bass, a professor of history at the College of New Rochelle, as saying: “It’s about the sense of fandom instilled by the likes of the Dropkick Murphys, the unofficial band of the Red Sox, who promote an imagined sense of identity for a New England fan built on notions of white ethnic identity.’’ Huh? We’re not sure what that even means, but Ken Casey of the Dropkick Murphys took it as an insult. Reached via text Wednesday, Casey said: “The band has been face to face with racism — confronting racists at shows and in the back alleys at venues where white supremacists waited for us because we have been outspokenly anti-racist our whole career. This woman’s rantings are seriously not worth the time it took write these few sentences.’’ Bass didn’t have any comment on Casey’s comments Wednesday.