The Leafs have not accomplish anything. Dubas took over a top 7 teams with playoffs appearances and the Leafs remains a top 7 teams with playoffs appearances.
Can you consider Dubas a failure, probably not bc the team is where it was when he took over. Is Dubas a success, not even close. Like all GMs, Dubas got in some good moves and also bad moves. NO point listing all of them as everyone here knows them already.
One thing I have to point out, Dubas is no genius and I think he is starting to understand that there is a reason why other GMs don't use out of the box ideas not bc they couldn't thought of it but simply they just ain't good.
Personally, if I am Dubas, I would really look into whats are available out there that could improve the team and nobody is untouchable except for AM and Reilly. If Jets want MM for Helly, make that trade bc Helly solves and masks a lot of problems for the Leafs. Heck if JT is willing to trade Pietra for JT plus, make that trade. If Bruins want Sandin and Willie for Marchand, make that trade. If Trotz is willing to come, fire Keefe and hire Trotz.
The goal is winning the Cup.