I wasn't a Marauder, Powertech, or healer and my guild's 8 man was optimized for the faceroll flavor of the month, so I stopped bothering.
The system sucks. I don't know how they'll change it in the future for solo queueing, but if its based solely off win/loss and doesn't take individual performance into account you can forget it.
Rated is going to suck until some much needed balancing is done.