I agree with the gist of your post, but those moves remind me of why I'm not that enamored with Yzerman's work in Detroit so far (though I do think he's a good GM overall). A lot of "1 step forward, 1 step back" moves.
- Mantha might be a flop, but he's a whole lot more valuable than Vrana, a guy nobody picked up when Yzerman put him on waivers, on top of swallowing the Panik cap dump. Of course, the picks offset that difference, so it's a decent trade overall. But then Yzerman packages that 1st rounder with a few others to move up in the draft to get Cossa at 15. Dallas uses the original pick to draft Wyatt Johnston instead. I dunno, even if you're a big Cossa believer, that doesn't seem like SY's best sequence of moves.
- Yzerman gives up a bunch of assets to get Debrincat's rights, which is fine. But he then proceeds to significantly overpay him. 8M for an undersized 65-70 pts scorer who's useless when not producing? At least he didn't give him term.
- Trading away a young top-4 Dman for a mid-range 1st rounder when your defence is as dire as Detroit's seems questionable to me. Maybe ASP will be a top-4 Dman in 5 years, but it's far from guaranteed.
And that's ignoring more minor trades that didn't quite work out, like giving up assets for the corpses of Jeff Petry and Nick Leddy, or swallowing Yamamoto's contract for Klim Kostin, who does nothing in Detroit. Of course it's easy to forgive this stuff when the team is bad, there's no expectations and the team has plenty of picks and cap space to leverage into assets. But still it gives the impression that Yzerman's pro scouting in Detroit is weaker than his amateur scouting, and that will matter more and more as the team moves out of the rebuild phase.