My guess (using my understanding of the Ortiz regime) is the transition was messy. Someone didn't do the legwork to see where everything was referenced, so when they started putting in new ratings, if they took the old ones out, they'd crash the game because little references here and there would call for a number that didn't exist.
Hopefully this is one of those things they'll finally get around to doing soon. It's really annoying to have a bunch of non-existent ratings in there.