IMO, the Sheahan situation was going to bring heat to Holland no matter how it shook out, regardless of the cap situation. Let's look at different scenarios:
A. Holland finds a way to keep Sheahan and he has another terrible to mediocre season: His trade value goes down even lower and if they can't get rid of him, they face having to give him a $2.075M qualifying offer that he likely isn't worth. Obviously, Red Wings fans would be torching Holland for not taking what he could get when GMs were apparently calling at the 2017 trade deadline, or when the Pens were looking for a 3C candidate. "Poor asset management!"
B. Holland finds a way to keep Sheahan and he has a rebound year: During Sheahans resurgence, Holland would of course get heat for all the players (regardless of where their careers ended up) he seemingly gave up on at or younger than Sheahans age. "See that's why they should've kept guys like Pulkkinen and Mrazek around!" That all ends however, when Holland then rewards Sheahan with a contract of questionable value and term. Once into that contract, at the first sign of struggle, Sheahan never recovers from being "another bad contract", which becomes another stain for Holland. "That's why you never give depth guys a a big extension!"
C. Holland trades Sheahan and he continues to play poorly for his new team: Most would probably be accepting of the return, but Holland would none the less be unforgiven for not having a crystal ball at the 2010 draft to show him that Sheahan would be another wasted 1st round pick, and he'd probably even get heat for not trading Riley when he regressed a bit after the 15/16.
D. What actually transpired, Holland trades Sheahan, who rebounds playing for his new team: Red Wings fans who were likely vocal in their displeasure of Sheahans 16/17 usage and overall season and wanted him gone for the best possible return, now turn their frustration to Holland for putting the team in a situation where he had to get rid of a player those fans wanted gone anyway. Narratives start to shift from "Why are AA and Mantha getting benched while no goals Sheahan gets 15+ minutes a night?!" or "Sheahan isn't scoring, why do they continue to put him on the PP?" to "He just wasn't used properly. Too many centers. Not put in a role to use his best abilities. If Holland hadn't signed Daley he'd still be here."
No matter what Holland did with Sheahan, it was going to be like tossing a boomerang covered in razor wire in a completely dark room. It was bound to come back and draw blood.
