First and foremost on the list is Timothy Liljegren. The 2017 17th overall pick has shown flashes of brilliance and by advanced metrics was a strong player for the Leafs, but when push came to shove, he wasn't among the Leafs best defenders. It's time for Liljegren to cement a top 4 role for himself, allowing for John Klingberg's suspect defensive ability to be sheltered on the third pairing.
Maybe Dubas' best piece of work of the trade deadline was acquiring Jake McCabe for a mere $2 million against the cap for the next 2 seasons. McCabe was good, and threw some monstrous hits in the post season, but he struggled, like the rest of the Leafs, in the second round. McCabe will need to find some consistency while keeping his physical presence at the forefront of his game.
Finally, the only pending UFA Brad Treliving rewarded with a new contract was David Kampf. Kampf has a surprising knack for scoring unexpected clutch goals, but his strongest asset is his defensive ability. As a penalty killer and a shut down centreman, Kampf is a valuable player for the Leafs. His new $2.4 million salary and likely role on the third line mean that he'll be expected to pitch in more on the offensive side of things.
We know that this team can only go as far as it's best players can take it, but there are 20 spots on the roster and it's absolutely crucial that all 20 are able to contribute. If Liljegren, McCabe and Kampf can find a way to do their jobs just that much better, they'll make it that much easier for the core to do theirs.