And at least 6 of the trades in that chart are for Samuelson.
The Wings have done pretty well as a team focussed on drafting, not trading. The last couple of years they've needed some trades, but they haven't pulled it off well - I mean, I'm sure Tootoo was a bargain, but he's also still Jordin Tootoo. Legwand seems like a good deal to me, and even if he's not a fix for everything that's wrong with the team he might be a sign that Holland's getting better at that part of the job.
Having a cap makes where players are willing to go a bigger factor (see: Edmonton), and while a lot of players might not want to live in Detroit, this is the sort of hockey team that can make a move worth it just based on that. That said, missing the playoffs would adversely affect that formula.