Yeah ok so you have your Reach/Zergbong team and your YellOw/Oops team. Those teams win more than they lose. Then you have tried out your Zergbong/Oops team which can't even win 2v1;

clearly they will use Reach/YellOw next time. And since Zergbong/Oops are useless, Reach/YellOw must always be playing 1v2 during teamplay. Now they will be able to do 2v4!