I'd like to contribute a protip for zergings. I've noticed that in my own game, but I imagine any zerg would work similarly... You can really get the upperhand if you manage to draw fire away from team members. I had no taking on my build (my game) but just dodging attacks and generally being in their face, I manage to draw their attacks to me and dodge them, and my team not only kept doing decent damage but they also didn't die so it really helped out winning the tide.
In GW2, that might translate into having one guy branch off and generally getting the opposite team wasting AoE's and whatnot trying to kill him instead of doing more useful damage against the group. With a fairly defensive build, you might be able to do that a while, go back to recover, and do it again.