You can't rag on him for 5-17 without giving him credit for having them up above Tampa earlier in the season. You don't get to count the bad and ignore the good.
The Wings collapsed because while they had a really fun and miraculous end in these last three games... they really really lacked difference makers. They had Raymond during that stretch where they lost 7 in a row. Kane slowed way down, Seider stumbled pretty bad, Debrincat disappeared and after enough games of dragging the team to a close loss, the goalies started falling apart too.
While the team was improved... they needed the depth to carry them through but when Larkin went out, they didn't have any kind of 1C facsimile and it killed all of their lines, not just the top one.
This reminds me of the same stupid shit with Blashill where a certain HFB member who is no longer here and shall remain nameless thought that firing Blash and putting Bylsma in charge would make the 19-20 Wings play .400 hockey.
Coaches, outside of the true greats, don't have the impact you're stating. And coaches, outside of the nincompoops (like Torts who burns every bridge within a year and a half) don't have the impact you're stating. It's talent, it's talent, it's talent. And the Wings by their own design were treading water until guys in GR can season up and their cap could come back into order.