Left 4 Dead he wins plenty often, online and off. But for some reason, anytime he's not having a good day, it's cause the game is aiming for him exclusively. I think he's just full of himself.
I learned this lesson the hard way some time ago. I was playing Conquest: Frontier Wars against him and a few AIs. I surprised him with a large fleet, crippling and destroying his main fleet before burning his home system to a cinder. He rage quit, leaving the hardest AI in his place. It make a valiant effort, but I burnt that AI down too.