man, you shouldn't have to learn who your team mates are. they should be easy to distinguish between the enemy.
and theres a difference between someone being durable and being too durable. i walked up to a guy and unloaded my flamethrower at him. it just barely did half damage, he then just ran away.
and dont get me started on all the snipers. that seems to be the only weapon that everyone uses and manages to one hit kill.
and of course once if your the first one to lose a building, the games pretty much over.