I dont believe that anywhere near as many players in the league are taking discounts to stay with their teams...that's a dumb, naive thing fans overblow and make up everytime something that appears team friendly happens, particularly with the earning potential in this sport being so much lower than the other major leagues.
I've never bought into the narrative of Slavin being the most underrated player in the league. I mean, it's clearly either that the league doesn't actually agree with that (hence him being paid like a good #2 defensemen and not a #1), or he/his agent got fleeced. I think it's the former...the league probably just doesn't see him in the same light as fans do, and the league is usually more correct than fans are.