Huge disagree. 80-90% of the blame goes to the players IMO.
Horvat was coming off a career year in his contract year and wasn't willing to sign at a discount... he wanted 8 years at 8.5M per even though his career high was 61 points. Canucks didn't want to sign a 60 point offensive center to that type of extension into his mid-late 30s. In his Islanders career, he's continued his career trajectory has a 60 point guy. He has 41 points in 56 games this year, exactly a 60 point pace. The management team already signed a comparable contract in Miller who is the far superior player. They managed to trade Horvat and flip the assets for Hronek, who's been great for us. I know you didn't mention Horvat by name but it helps to add context. This is probably an A in terms of grading.
You indicate that Management sold low on Miller... but isn't that just using the power of hindsight? At what time were we realistically able to sell "high" on Miller? During Miller's down year in 2022-2023, he was shopped before this NMC kicked in but teams were scared of the extension and the offers weren't good (weren't much better than today if at all). The year after, Miller returns to form and carries us to Game 7 of the Semi-Finals and was our best player in the playoffs. We could have gotten a better return but why would we trade our best player as a top 5 team in the league? Fastforward to this year... Miller has been awful and some sort of altercation or event occurred that directly lead to his month-long leave of absence. Again... how could management anticipate something like this happening at all? This lead to them having no choice but to get rid of a locker room cancer/distraction. He had a NMC and was having a down year... the fact we got MP, Chytil, Mancini and ridded ourselves of Deharnaias and Heinen is actually very good given the circumstances. This is probably a B in terms of grading.
Petey's terrible play is also management related? I don't understand what you want this management team to do with his on-ice play. They traded his "bully" and gave him keys to the franchise and he's looked even worse.
Saying the management team botched the entire thing is such a dumbed down answer. The environment is extremely dynamic and everchanging in sports... you can only operate and make decisions based on what you know at the time. No executive in a suit could have predicted or prevented JTM destroying the locker room and Pettersson's fall off a cliff happening simultaneously.
The current state is what is and the management has extremely difficult choices to make from here.