On my undergeared mage, I get undergeared teammates and on my geared rogue i get fully geared teammates. At first I just thought it was bad luck and all but then I decide to do a little test...
I did 5 bgs on my rogue, and 5 on my mage. The 5 bgs on my rogue i got about half full cata players and half cata/ruthless, in general that is. On my mage, I got mostly people who had 377 gear and 333/346. Out of all 5 bgs, I had 1 full cata player....