We were 6 players in the lobby, all ready, but the host said that he couldn't start the game because someone was trying to connect.

Shouldn't that be a bug? Who cares if someone is trying to connect when all slots are full and everyone is ready?

But then, a second or so before launch, a player simply vanished from his spot, and the game launched into the loading screen, with a "wait for other players" popup that lasted about 30 seconds.

Once in the game, I find myself in a 2v3 game, with a ping 0 player as my only teammate, and on the other team, two players have pings, and one other has ping 0.

First of all, I thought that the ping 0 in this patch was supposed to be replaced with the text AI?

Second, if the game is now going to start behaving badly before a match has even started, the need for not penalizing quitters is greater than ever. There needs to be a way to end a game cleanly, ahead of time, so I don't have to roll my thumbs for 20 minutes while I watch two player and one AI steamroll me.