focus on all your stats.. Those saying a high k/d is needed may not have considered that accuracy and headshots all play parts too..
Show the game you can reach round 22+ for example..
Do this once a night at least if you can..
Each night you play a tally mark will register, and youl be filling your 'live database' with good stats..
It's gonna maybe think.. 'hey this guys gone from killing about 300 zombies in one game with 10 headshots and 3 downs, to consistent high rounds, killing 500+ with third headshots, no downs, and good accuracy'....
Everyone can have a better game then me, or the dude with the knife... But how often can you do it? ;)