Couldn't help but throw this out there considering this thread is still fairly recent:
http://news.ca.msn.com/top-stories/video-game-rage-violent-imagery-isnt-the-trigger-researchers-say"While rage stemming from video games is common, there are different theories about what triggers it. Some suggest it's the violent images in the games, but a 2011 study conducted by researchers at Brock University indicated that the most influential factor in video game rage is the level of competition involved. "
"Adachi concluded that people who played highly competitive games behaved more aggressively than those who played the less competitive games. "
And according to DG, most ragers are CoD players

Apply a little deductive reasoning and.....