Instead of the Microsoft tru-skill system how about something much more simple.
Say you are playing LW.
Player1----45 skill in Playlist
player2----44
Player3----43
Player4----42
Player5----41
Player6----40
You gain 1 level for each person you beat of a higher rank than you. And you lose a rank for each person of a lower level you lose against.
Let say it finishes this way:
Player6
Player2
Player5
Player3
Player4
Player1
If player 6 wins the game he beat 5 people that were better than him he goes up to 45.
Player 2 lost to a player that is lower than him, but beat player 1 so he stays 44.
Player 5 beat 3 persons that were better than him, and went up to 44.
I know it is not a perfect idea, but it is something to work with.
So tell me what you think of it, flaws and advantages and amendments that can be done.