If you guys are so obsessed about your stats then as Simon said the old stats can remain, although they wont be included in any detailed stats (but they can be displayed in your total kills, exactly as it is now!) because the new stats will take many things into account such as the vehicle used, the weapon used, whether it was a DB or not, whether it was done in a tank or a helicopter, and much more.
This way we can generate more interesting stats and do other things with them, like check who killed the most players on a certain day, or who killed the most players with sawns or with tecs or with a baseball bat or w/e. This way stats would be more than just a number, it would actually read more into them.