I don't understand what narrative you're trying to spin here. As far as I can tell, Sanheim's journey seems like the opposite of what you're implying he suffered from early in his hockey career. Just read articles leading up to his draft. He was not on anyones radar as a "special" player.
From my perspective, he struggled like any other young D does. The only difference being his coach has this odd fetish for "safe" plugs and a no nonsense policy for rookie mistakes. How can you expect a young kid to grow at a rapid pace when he's getting his playing time slashed for inevitable rookie gaffs?
Also, and I'll reiterate this, using Ghosts rookie season as a benchmark for Sanheim is completely disingenuous for the most obvious reasons.
Sanheim was drafted #17, he started slow his draft season but finished strong. His two post draft seasons he dominated the CHL on talent. He was bigger and faster than most of his peers. And like a lot of skilled CHL stars, he isn't a fundamentally sound player.
Sanheim was clearly overmatched when he came up last year, and the coach sheltered him as much as possible, buying time for him to adjust (easier matchups, more minutes at home than on the road). He was better after he returned but still far from being a top four defenseman in the NHL.
Watching Sanheim in the AHL playoffs, I didn't see a player driven to show the FO that he belonged in the NHL, he seemed unfocused, and was outplayed by Myers.
We'll see in camp if Sanheim has grown up physically and mentally, he wasn't held back by his coach, the same coach who plays Provorov more than any veteran - he was held up by his lack of strength, his soft play and his lack of focus. It's up to him to show he's learned from his rookie year and to kick butt and take no prisoners. In the NHL, playing time should be earned, not given.
I'm skeptical about Sanheim, I'm totally confident in Lindblom, and it's from watching how both players dealt with adversity. Lindblom was a 5th rd pick who dropped due to doubts about his skating, he worked his butt off, excelled in Sweden, came here and was sent to the AHL, worked hard to improve his game there, came up, showed a nonstop motor, struggled in the playoffs, was sent back to the AHL and instead of sulking worked hard to make an impact.