Before 3.3 was released, i'd assumed that the random groupings would either put you with people of a similar gear level, or try to balance gear levels (one top-end in group means one low-end to balance), as gear level seems to be the only way to work out how good a random person is likely to be.

But i've had groups with my main where everyone was 5k+ gearscore, and groups where i'm the only one above 4k, and with my alt where everyone's low, or i'm the only low one...

So is it just totally random, or does it try to match groups by some other criteria?