There's a video many people have watched of AHL player Brian McGrattan getting knocked out in a fight. It's a tough view for many, and the fans' behaviour is troubling.
McGrattan has played for a laundry list of teams and last had something like a full season in the NHL in 2013-2014. He signed on to the Anaheim Ducks this year as a free agent and has played 36 games for their AHL team. He has 8 points, a decently legitimate number of shots on goal, and 94 penalty minutes.
There is a perception, partly based in reality, that the AHL has a fight every game.