Game pretty much takes the player worth for each player, adds them all for each player, and balances accordingly. A lot of the numbers are very off. The kd used in the code isn't what's necessarily on the site, but some odd function involving them.
Messing with the autobalancing itself may make things worse. Remember when we had 4 vs 40 battles sometimes? There's also no way to test it. People's pings were going up to 1000 when trying to join Tydeus' server.
Then there are times where short term success is radically different than long term success. I've seen the same team compositions completely destroy the other team, then get destroyed themselves the next round.
It's just risky overall unless the people who coded it in were to change it.