That's a bit unfair imho, because there can join a good player for first time on server, own us, and stats goes down... But, stats aren't so important [; .
Well everyones stats will go down..
besides stats in TF2 are a bit dumb anyhow. Just look at or top 10 and ponder what classes these people play. Soldier, Demo, Medic, Heavy and Sniper
All classes that are sure to get a lot of kills (assists) in the hands of any decent player. Its nigh impossible for scout/spy/pyro/engi to get in there, simply because they are far more circumstantial than the soldier, demo and heavy+medic pairs. Besides the fact that anyone who wants to play those classes on maps like dustbowl, steel, badwater and gold rush are at a rather large disadvantage. (Engineer just seems to be an average man tbh)