Granlund is a tough one to really assign a "value" to. I think there's probably a lot of disparity in how different teams view him, depending on how their team is set up and what they're really looking for.
He's been pretty up and down in his career. Is he a 60pt complementary Top-6 Forward? Or is he a sort of 30-40pt middle-6 filler without any sort of defined role?
He can play Center...but he's certainly not what you'd want in a lockdown matchup #3C on a contender. And if you're a team trading for him to center one of your Top-2 Lines, you're probably weak down the middle and not really a contender that's going out trading for guys in his age range. Maybe you deal for him as a Top-6 Winger, but there's still gotta be some wariness when it comes to the fact he's really only been particularly productive when he's getting "top minutes" while playing "3rd wheel" to bigger play drivers. Koivu/Zucker, Forsberg/Duchene. Has a good complementary skillset to contribute to that sort of arrangement, but still kind of a coattail rider.
To me, he's just sort of a "super premium utility filler player". Which, at $5M is a really hard sell. At $3M? That starts to make a lot more sense. But i'm still not sure the market would be there to fetch a big return. Especially with years remaining, that you'd be committing to...not really knowing exactly what version of him you're going to get.
It's not that he's a bad player. He's just not particularly impact in any specific area of the game. Hard to point at any specific thing to hang his hat on. Tough to give up significant assets and commit to a guy like that for multiple years. It's the same issue he ran into when he hit Free Agency and had to wait around a little bit and take a smaller than expected deal to better establish what exactly he is as a player. Yet i still don't think he's settled that.
Not sure where that really leaves his "value".