kind of like what is going on at GoldToken.com with their ladder system. As long as you are on the ladder, you will have a game going. If you win, you move up. If you lose, you move down. And then you are again matched up with someone else in the same "rung" and play again until you move up or down. (Played games counting towards the BKR)

Then if you don't want to play (or can't), all you would do is lose a rung - and would not affect the BKR. That would be good.