If I had the power to alter the GM AI of the game, I would make sure to start small. The occasional bad lines or bad subbing, maybe even pulling a goalie for no real reason. As the league gets accustomed to this, I would start to ramp up the bad decisions. I would play goalies as skaters and skaters as goalies. Play lines for whole periods without subbing anyone. Randomly cut, sign, and trade players on a whim, usually as an overreaction to one good or bad game. I would still keep these "random" events pretty rare. ISFL puts up with the sim doing stuff like this a couple times a season. Then after that became more acceptable, I would step it up and start to target random teams. Weeks of having your goalie face off, never making subs, basically just tank one or two teams. I would turn the league into chaos.