He was pretty bad at it. Muzzin is the only effective one he brought in who was here for a while under him. The problems with Dubas were twofold. First, he failed to identify toughness that was useful, either getting guys too old or just plain not good. Second, the Leafs didn't value toughness and pushed a pacifist mentality so that even when those guys were brought in they were joining a club that never engaged physically, so what was the point? You bring in Nick Foligno and one of his first games Keefe is telling him not to fight? The toughness Dubas brought in did not adequately fit or replace what we lost over his time here.
Here's a look at how Dubas handled toughness during his 5 seasons at the helm:
2018-19 Komarov and Martin were lost and while I get that they're bottom-six players and some might not value what they brought, their games are valued and they played a role on Islanders teams that went deeper in the playoffs than this franchise has in decades. Polak was also lost that season too, leaving us with a soft D-Corps until Muzzin was brought in. Kadri is on an island, tries to do too much against a Boston that was just bullying us and the rest is history.
2019-20 Even more toughness is lost with the Kadri trade, which would be fine if it was a good trade but it very much wasn't. We got a terrible fit in Charmin-soft Barrie and a tweener in Kerfoot. He attached Clifford to the Campbell trade but had to trade Moore to do it so at best that's a wash. Leafs had their worst season of the Matthews era, though that's not entirely because of a lack of toughness. Babcock was a jackass and as a whole the team was just worse off. Also this was the season of the infamous Marchment for Malgin trade, a microcosm of Dubas' philosophy and blind spot.
2020-21 He brings in a past his prime Simmonds and signs Bogosian and Vesey to one year deals for bottom pair and middle six grit. Simmonds was cooked, Vesey didn't find a place here and was waiver fodder, and Bogosian was good, fair play there. The Nash trade on it's own is ok but bringing in an old and injury-prone Foligno to essentially block any chance of regular season playing time because of the cap was terrible, not to mention Foligno was just bad. These moves also didn't work because these guys were basically mercenaries with expiring contracts. If there's no real will from the core guys or coaching staff to mix it up or fight back why should they? I know Foligno and Simmonds tried but it wasn't enough. He does have the sense to draft Knies.
2021-22 Out the door goes Hyman, Bogosian, Foligno, and Nash. Simmonds is re-signed to be an enforcer but he was the least effective toughness. Bunting and Ritchie are signed and while Bunting isn't strong or tough he at least plays like an agitator and got in opponents faces. Ritchie just sucked. He trades for Lyubushkin but that's it on the toughness front. This season was probably the softest the forward group had ever been. Kerfoot, Mikheyev, Engvall, Kase, and Kampf were all the same type of temperament and similar playstyle and they littered the bottom nine. Bunting was a rat, Spezza had heart, and Simmonds tried to enforce but that was nowhere near enough. Dubas signs McMann to an NHL deal at the end of the year.
2022-23 Lyubushkin is out, no great loss. Dubas does a bit of work around the edges, bringing in Aube-Kubel and Aston-Reese for the bottom six (only one of those guys worked out) and Benn for defensive depth. There's some softness subtraction with Mikheyev and Kase leaving but he makes sure to give Malgin one more shot to try and show that there was something there now that Marchment has taken off elsewhere. Malgin experiment fails and he's traded for depth. Things look to be more of the same old same old until Dubas pulls off the biggest TDL this franchise has seen since 2003, bringing in O'Reilly, Acciari, McCabe, Lafferty, Schenn, and Gustaffson. The first five guys all played with an edge and brought more to the table than just run of the mill pugilism. O'Reilly was a 2C, Acciari was a defensively sound 3rd line wrecking ball, McCabe was a tough top four defenseman, Lafferty was a gritty 4C penalty-killer, and Schenn was a heavy third pairing defenseman that blossomed into more here and played on the top pair with Rielly. Knies is also promoted and helps fill the hole left by Hyman.
None of the toughness Dubas tried to bring in beforehand outside of Muzzin even came close to the quality that he found that trade deadline. 4 previous seasons he couldn't identify any gritty players who fit well and played outside of the bottom pair or 4th line. It's absurd but it's true. This came at a great cost mind you but it led to the only series win this franchise has seen.
Now with Treliving we've got a defence that's full of mean SOBs with McCabe, OEL, and Benoit. The forward group has a good amount of physicality and nastiness that can actually play with Knies, McMann, Domi, Lorentz, and Dewar. Reaves isn't in the ideal playoff lineup but there's something to be said about his reputation and the camaraderie he brings. Dubas brought in Clifford and Simmonds so it's not like he was completely against enforcers himself.