Personally I don't like this idea, we already have a ranking system in place and there is already enough work to be done on the 5.0 beta at hand already with polishing up the matchmaking.

Though with the matchmaking a previous suggestion I had made a long time ago could be revamped. I has suggested a system of Daily/Weekly/Monthly challenges where upon completing the challenge a player would be rewarded for doing so.

You could implement this into the matchmaking system similar to what you're trying to do. Though like people pointed out, its easy to abuse something like this with alts to farm TC.