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.
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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.