frankly, if the good bear manages to keep ahead of the mages and do his job, the rambo mages can do whatever they want.
if 4 bears take turns passing the hockey puck, the poo mage can barely hit a few creeps with his aoes, and never the same ones for cumulative damage...

that said, I think the worst team might be one full of dual-sword melee birds, bear or mage aside. that fact that not everybody has dual swords is the only reason this is not yet a minimeme xD