Okay, it is not like StarCraft II is balanced for team games in any way. It never has been and Blizzard seems to prioritize carebear team games over balance. Nothing new.
And Zerg has always been the worst race for team games. Traditionally it has mostly been a map design issue. The shared bases with an easy-to-block entrace removes the threat of early pressure. That sucks and make games less dynamic.
But the newest patches since blizzcon has removed any illusion of Zerg being viable in a team game. I kinda like the new battlecruiser, but team games allows you to mass them making the late game air-show even more ridiculous than it has been before.
So team games is Terran and Protoss only until next patch.