It's a good idea but needs tweeking. First I agree with Donosaur's point.
Secondly they need to have transparent guidelines on how these rankings will affect matchmaking. Having stricter protocols on who fights who would go a long way to legitimizing MMA. The current system of who will sell the most PPV's does nothing for credibility.
Hating on Anderson Silva before it was the cool thing to do.
The idea of a "true number one contender" is the stupidiest MMA idea to be perpetuated by fans and media, EVER.