Not sure where that reputation comes from because I don't see it. He lasted only one full season his first stint in Montreal. I also remember vividly Julien brilliantly inserting Kovalev on the 4th line after Gainey traded for him.
He couldn't last one season in NJ after being ejected by the players who recognized he was a fool.
He was 1 shot away from being fired in Boston after 4 seasons. He greatly benefited from a stack team in Boston with a Norris winner, multiple Vezina winners and a 4 times Selke winner and still only managed one Cup and an additional final appearance but otherwise didn't make it out of the 2nd round 8 seasons out of 10. The Bruins regularly underachieved in the playoffs under him. He also contributed to Kessel and Seguin being booted out of Boston, ensuring that this potential dynasty was short lived. I thank him for that.
He was awful last playoffs against the Rangers, got completely outcoached by Vigneault, and had no solutions all series long.