I agree 100% that there will always be competitive players in the community, and there is absolutely nothing wrong with that. But those players don't need to act like fools when they kill other players. I'd actually look up to a good amount of players in the top clan community if they acted mature while in game. A good example to take from this is the Major League Gaming community. The general age is around that of what you'd expect to be the really competitive players on Minecraft (maybe slightly older), and they tend to act extremely mature when out at competitions where everyone is watching. Consider when the top players play on the public servers of MCG, that everyone is watching them, so they should probably not act like a 12 year old who just got his first Xbox and Call of Duty that day and is ready to "rek sum scrubs yaaaa".
Oh so many fond memories of CoD4 and MW2.
Edit: Grammar
