What makes you say that, though? All people in the CoD games care about is KD, when in reality you should be caring about how much fun your having. Games are supposed to be fun and a way to relax, not a challenge where you're yelling at the TV lol.
I'm good at CoD so I never care about my k/d. Also BF3 is way too slow for me, I like the fast pace of CoD.