BPR is what I was trying to get at with Op3, just forgot what it was called. It seems to me to be a very accurate system, and paired with a few other things, such as BlackOps's 'Performance in last x-amount games' and the amount of time you've put in to the game, would be the most logical system to use.
With the performance in previous games, if you are generally a, say, 1.4 KDR player, and the last 5 games you've averaged 0.9 KDR, the matchmaker would attempt to put you in a match/lobby with an average KDR in between 0.9/1.4. Or, the same idea if you've been doing something like 1.9 KDR for the past few games.
(Thanks for all the feedback too )