I've read that certain things WILL be ranked, but that it will NOT determine your level.
It's just for bragging rights pretty much.
So you can be a lv50 with uber guns and a 2/40 KD ratio. That won't effect your level but only your standing on the ladder with other lv50's.
And I'm sure if you ended up with the most kills through out the whole battleground fight, you might get an EXP bonus or something. It's only fair. That's my two cents.