Came close in a 3v5 one time. I was in a game where 1 never connected, and then 1 left after dying at the first fight at the windmill.
Our remaining team was Caitlyn, Mordekaiser, and Cassieopeia.
That sounds like a pretty garbage team for Dominion. But let me tell you, that snake lady held bottom like a boss. And I was playing Caitlyn and me and Mordekaiser just went around killing everyone surprisingly easy.
The problem was that none of us were mobility champions... We couldn't capture enemy base points and hold them without being overrun 2v4 very quickly. We also had a lot of trouble defending our mid point, because a lot of action was at the Windmill so we were always up there.
We came pretty close because kills remove Nexus health up to a certain point. But I think after that, it was extremely hard to hold a point advantage.
I was sad. The 2nd leaver was a Poppy. We could have won a 4v5 if Poppy stayed.