This firing rests squarely on the shoulders of the players and Don Sweeney.....In that order.
I don't disagree, but I still think the firing of Monty was correct, or at the very least inevitable. He'd visibly checked out in the last couple of weeks, was not saying anything of any substance, and had basically admitted he was out of ideas as to how to turn this team's fortunes around. As I've said before, he had all the look of a man just waiting to be relieved of a burden.
It's a weird situation. Monty's regular season W/L record is exceptional, and it's only a few months since he got 109 points out of a team that certainly wasn't close to that on paper. And the current issues need to be laid at the door of the players - the stars especially - and Sweeney first and foremost, as you said. I'm also usually in favor of patience with coaches, and I think the rate of coach turnover in the NHL is ridiculous. But for all that and as harsh as it is Monty had to go, IMO, because he simply had no answers as to what to do with this current roster. Perhaps no-one does, but this is Boston and you have to try. Can't sack the players in the short-term, and I doubt any sort of meaningful possible trades are yet available. So the coach has to be the first to feel the consequences. Not fair, but not wholly unwarranted either.
But of course it shouldn't stop there. Barring some sort of miracle turnaround, the heat should come on the players and management next.