I'm honestly now sure what it does now....
But this is how I could see it working.
List of weighted factors to determine balancing (items at top of list have more weight than those below):
1. Banner balance
--- Evaluate result of banner balance and remaining players ---
2. Current score
3. Current KDR
Since banner balance is the strongest factor in the equation, what it needs to do is sort that part out FIRST and then evaluate the result - if the banner balance part of the equation leaves one team VERY STRONG in terms of score/kdr/numbers, then it needs to throw any other players who are doing well in score/kdr on the OTHER TEAM
This is the biggest current problem with the balancer and its usage of banner balance. It will throw CLAN X all on one team and they are mostly all doing very well, but it doesn't seem to properly counter that by giving the other team enough "powerful" players to counter CLAN X. If CLAN X is dominating it's members will typically naturally end up with good score/kdr. Between that and numbers, the balancer needs to counter their effect by giving the other team as many players who are performing well as it can. Surprisingly though, it often fails to do this and will put CLAN X -AND- many other well performing players (not in Clan X) all on one team, and barely any sufficient counters on the opposite team.
An alternative to using current score/kdr would be for the servers to track each player over time (kinda like battle tracks your KDR) - except no one, even you, would be able to see this number. Basically it would be average score per map and average KDR (one for battle and one for siege).
Then, the equation would use THIS information in the equation instead of CURRENT score/kdr.
NOTE : I would actually be ok with these additional statistics (average score per round and/or map, and siege KDR being visible to the player on their character page like their battle KDR currently is. I would not make it public just like the battle one isnt just because that leads to a lot of playing for the wrong reasons).