Player time-out after leaving game

There has to be some type of penalty when players leave games early, not so much for large scale combat, but when its 4 v 4 and a player isn't doing well they will just leave and start a new game - that should be like a 5-10 minute time-out from joining another game in the same category. If they really had to leave, then they wouldn't mind and if they are that angry it gives them a cool off period. I'm tired of 4 v. 4s turning into 4 v 2 or gets as bad as 2 v 1.