Welcome, here's my awful idea of balancing the game:
Add all the other mercs in the next patch.
After playing against a team of only Fraggers and Auras, I reasoned that because of the limited number of characters, the "overpowered" mercs were discovered faster and no-one was willing to try out the others. Adding in the other characters would give more choices and -maybe- make people stray away from playing as Aura and Fragger all the time. That'd be nice.
I know this idea is terrible, but hey, thought I'd share