If you are supporting your team you can still play for disruption of strategy in key moments, be smart about your psychic scream or your hammer of justice, those few seconds you buy or disrupt the other teams attacks could be vital for second life money.
The more you know about the opposing classes and how they can work out within the arena, the better off you are to devise a counter quickly. If you can discern quickly how Demonology and Affliction warlocks differ, how Fury or Arms differs, what to expect from a frost or fire mage, if it is a shadow or a holy priest, you have already got a good advantage in knowing their advantages and lid imitations.