Old-ish reply, but I had a leaver which cost us the game. That sucks so much more. We aced them at baron 4v5 at cost of 1, but couldn't push enough since we had an inhib down. We could win teamfights, but with an Amumu ult any fight would've turned into a 0-5 ace. Oh he was the kind that did nothing wrong, but everyone else sucked.
Then I met him again 3 hours later. On the opposing team. And I stomped his ass. Felt good.