Dubas is an objectively good general manager. He was not perfect by any means and was partially hobbled by some of the dumbass mistakes of his predecessor, but the Leafs enjoyed great regular season success while he was running the show, they just couldn't parlay that into playoff success, for a number of reasons.
If and when he decides to come back he'll absolutely kill it.
Personally if there was a mistake made it was handing all that money to John Tavares. Everything else that tripped them up can be traced to that one signing. Suddenly the other members of the core were not about to take any sort of discount, and then Tavares himself began to decline and now doesn't even come close to justifying that massive contract.
I also think, in hindsight, that despite his immense talent and hockey sense, that Mitchell Marner ain't The Guy. Too often he's a ghost in the postseason and in big games. He could very easily flip that narrative and he's still relatively young but I just don't think he's ever become the elite gamebreaker that contract he held out for calls for.
