You have forgotten the campers they also get a KD of 10 if they are a complete squad of hardcore campers that go to usually unreachable rooftops or single persons that are so good with suppressor with unlimited ammo as Support. I mean you can play Assault with ladder and spawn beacon, climb up somewhere put the beacon there and then spawn as Support on the beacon, this way you get to unreachable spots and have unlimited ammo. If you are in a very unusual position ppl normally don't look at and use a suppressor the chance is there you can get long camping kill series.