It's not worth the risk. First, if a Power 5 school goes after all of these overachievers there will be hell to pay with the boosters and alumni for having a rotten gawdawful recruiting class, based on the metric for judging these things. Right there the coaching staff is already on shaky ground. Not only that, there would be pressure from university administration to help with their "diversity quotas", the only way most blacks will qualify to go to the school is via an athletic exception. Then say a white running back is recruited to scholarship and he doesn't pan out, that's a HUGE black eye. They could recruit 6 black RBs that plain suck, but nobody would notice. Just a few ways that the Caste System works in college football recuiting.