I personally like Kyle Dubas, he is a personable, well spoken guy and he seems to do right by the players (like staying with Mikheyev at the hospital for a few days) which I believe is huge for developing a good reputation as a team and organization. However, with that said, there are some things that could definitely do better in the future.
His negotiation tactics have been underwhelming. The fact that Marner contract details leaked out for over a year and a half made the final deal look very bad (originally Marner wanted $9 mil but Leafs said no, then Marner had his big year and his holdout). The Tavares negotiation leaks made him look better though (Tavares turned down 7 yrs @ $13 mil from the Sharks).
And while the Muzzin deal has been very good for the team. Dubas in the past 2 trade deadlines did done nothing to bolster the Leafs obvious lack of depth on defense. 2 years ago Gardiner was already out with a back injury and Dermott got hurt right after the deadline but Dubas did not try to build any depth in case of injury. And this year the Leafs had Rielly, Muzzin, and Ceci out yet still did not try to find help at the deadline.
If Dubas paid the low price to acquire a depth guy like Beaulieu last year or the modest price for a RHD like Demelo this year, I think the Leafs would have beaten Boston last year and beaten Columbus this year.
Those are my 2 biggest pet peeves about Dubas. I think he has the potential to be a very good GM in the NHL, we as Leaf fans just happen to be dealing with the growing pains of him learning how to do his role properly.
