Baseball players choose their walkup tunes with little regard to fan allegiances in the music industry. When I was about 10, my favorite Mets player, an outfielder named Derek Bell whom I favored because of his interesting mustache, approached the plate to the opening strains of Jay-Z’s “Big Girl.” The tradition goes back much farther, at least to Reagan’s campaign, during which Bruce Springsteen asked that Ronald Reagan not use “Born in the