TNA gets a consistent 1 rating on cable. If what they pay for a 1 rating is better than what they would pay for a .3 rating with a Charles in Charge/Joanie Loves Chachi block, then they keep TNA. If not, you'd have 2 of the greatest themes in television history on Spike.
Ah, but that's the genius of it. Instead of being 'blamed' (by the online crowd at least) for Raw's average ratings, he could go to Smackdown and then claim that their lower ratings are due only because of the Friday slot.