As it is right now, it is the average kills per game of people who have never prestiged. For some reason, the average kills section takes all of your kills and puts it with your games played on the current prestige you are on. So if you go from 0 prestige to 1st prestige with 6000 kills and play a game, your average kills will be 6000. Say you then start the next game, but can only get 10 kills, your average kills will drop to 3005 and etc.

It would be more meaningful if it incorporated all the games played, not just the ones on the prestige one is working on...