It’s not most but it is a big chunk of the team that has his fingerprints on it. A third (8/24 players) of this team heading into the playoff is his doing. Biggest pieces left that were pure Dubas moves are our 2C, 1LW, and our 1/2LD.
Matthews (Lou)
Marner (Lou)
Nylander (Nonis/Shanahan)
Tavares (Dubas)
Knies (Dubas)
McMann (Dubas)
Domi (Treliving)
Holmberg (Dubas)
Robertson (Dubas)
Laughton (Treliving)
Lorentz (Treliving)
Jarnkrok (Dubas)
Kampf (Dubas)
Pacioretty (Treliving)
Rielly (Burke)
Tanev (Treliving)
McCabe (Dubas)
Carlo (Treliving)
Ekman-Larsson (Treliving)
Benoit (Treliving)
Myers (Treliving)
*Hakanpaa (Treliving)
Stolarz (Treliving)
Woll (Lou)
*11 (Hakanpaa is still a massive question mark so more like 10) players are pure Treliving moves. This includes our 1G and most of the defence including our 1RD and 2RD. The head coach is also all Treliving.
Lou leaves behind our 1C, 1RW, and 2G. Nonis, but really Shanahan given the story around the 2014 draft, drafted Nylander, and Burke drafted Rielly.
Although Lou was the GM of Record for the three players you've put his name next to, I'm not sure how much credit he would deserve for any of the three.
For Matthews, I would say it goes back to Shanny firing Carlyle while the Leafs were in a playoff position and initiating a full rebuild (being a fringe playoff team was not good enough). Assist to Dubas for finding a way to move Kessel, and accepting a poor return because it was a lose-the-battle, win-the-war type move. Lou and Babcock also get credit for tanking to last place, but I would say Matthews is 15% Shanny/Dubas, 5% Lou/Babcock, and 80% lottery balls.
For Marner, he was drafted in the days of the five-headed monster (Shanny/Lou/Dubas/Hunter/Babcock), and it was definitely a group decision (EDIT: Lou hadn't been hired yet - so group decision between the other four). Woll I would give directly to Hunter (his one success). Hunter was hired by Shanny and ran the draft, so I don't think Lou had any involvement.
On the other hand, Dubas did build the whole scouting department when he took over, so he does get credit for being the overseer on picks like Knies. I also give him credit for Cowan even though he had been fired shortly before that, because it was still his scouting team and Tre even said he didn't get involved. But Cowan (and anyone else from that draft that turns out to be good) are Dubas' last contributions.
For Tre, by far his biggest contribution has been rebuilding the D, which I was hoping would happen when he was hired, given how good Calgary's was under Tre. I'd say he's 5/6 finished his job. Stolarz was huge as well. I also give credit to Tre for the drafts starting with Danford and others last year - even though Wes Clark was still here, Tre had been here a full year and would have worked with him on drafting strategy, etc.
Bottom line is if we see playoff success this year, it probably continues to be a Dubas/Tre hybrid team. And there's no need to exaggerate what one of them has done, or minimize what the other has done, just to suit a narrative.