Flamers will use any excuse
So I just played a game in which I went 12/4/10. I had two teammates swearing at me and calling me bad. We won the game. By a lot. But these two people insisted on flaming me. This is just an example of proof of flaming having nothing to do with poor play. It has to do with flamers being jerks. Really all one can do is mute people at the very first sign of negativity towards their teammates.