The REAL problem here is GTX.
Somebody said the low score players get moved, this is true. However, AFTER autobalance is calculated, people are like "F THIS!" and quit. So teams might go from 40-50 to 40-44 after GTXs.
It's not the low scoring players who GTX either.
So one team loses, decent players quit, the team loses again. When people don't quit, the teams seem to be more balanced overall. So I don't think there's an actual problem with the autobalance as there is a problem with people disliking autobalance and just assuming it's not working.
Then again I was just on the battle server, our team got absolutely slaughtered (I think we killed about 5/40 of them?) and the autobalance switched 2 players (cav) off of our team in exchange for their team killers. (-1 and -2 score* -2 guy suicided I think, actually) maybe some other unnoticeable changes.