Shanahan, Treliving, Keefe, Matthews, Tavares, Marner. I don't think any of them are to blame as much as Dubas. He set a terrible tone by letting the stars run the team, and holding no one accountable.
Lamoriello had to go - he was out of touch with poor free agent signings, and not allowing anyone to grow facial hair is a bit outdated. But that was the last time the players played as a team and not as individuals. Dubas went overboard in trying to do a 180 on the tone to prove that he was progressive, and that's what sunk us. Not Shanahan, not even Keefe's coaching decisions. The tone was set from up top. Because Shanahan allowed Dubas to set it, it started from him.
Keefe has coaching warts and he'll have a great career and future. But it was the tone that Dubas set that influenced the way Keefe managed the team (in my opinion). The 5 years of Keefe may have looked very different if Keefe was taking his cues from someone other than Dubas.
I think he may prove that elsewhere.