I really don't think i'd want Tom Wilson on a 7-year deal at all. Right now, he's probably not that far off being "worth it" as a player who can bring a pretty unique and highly coveted "impact" skillset to the table. When he's engaged, few guys can offer that combination of physical intimidation + getting under peoples' skin + legitimate top-end goal scoring ability and decent complementary offensive skill all around.
It's really not the type of player that has historically aged super well though. That kind of game tends to take a real toll on the body, even when they're the one dishing out most of the punishment. He seems fine for the moment, but he's crossing that threshold into the danger zone on the wrong side of thirty...and that sort of decline can send that type of player right off a cliff at any moment at those ages.
I'd frankly, probably prefer to have him "overpaid" a little bit more in the shorter-term, than be a bit more of a "bargain" right now, but on the hook at that price until he's 37 or whatever. Obviously team situations would play into that a little bit...if i'm in a position to go "all in" over the next 3-4 years, i guess i just live with the consequences later. Very possibly end up with 2-4 years of basically an "overpaid mascot" tough guy who can't keep up with the game at the tail end.
But on a 7-year deal, it's really just a matter of trying to guesstimate when he'll fall apart.
Right now, he's worth more than $4.5M pretty comfortably. But in 3-4 years, there's a reasonable chance that's still a painful contract AAV to have on the books. So where does it balance out? right now, $6.5M doesn't seem outrageous to me. But in a few years, that's likely to be an absolute albatross. Just hard to assess that value fulcrum...when you're totally guessing at how long he'll hold up, and independent of "Team Context" to decide how much sacrifice down the line is acceptable.