How is it unbalaced? You get a certain amount of kills without dying and you get reward for it according to the amount of kills. Mass Effect Multiplayer is the epitome of unbalance
Scenario:
My team mates are noobs and feed > I get nuked from outer space.
Seems completely balanced, because I totally deserve to have helicopters shooting me to death because my team mates played bad, or some idiot threw a grenade and got 3 kills early on. It doesn't take skill to play these games, therefore you shouldn't be rewarded for what is essentially glorified spray and pray; which pretty much sums up modern military shooters.
Seriously, go play some REAL fps games, and then you'll see how poor games like CoD really are.