But he is not a UFA yet, and that $4-$4.5M seems like a UFA deal. He's got a couple more years before he can be UFA, so giving him UFA money doesn't make sense.
If trying to sign him a little longer term, you look at what he could earn in short term. Maybe $2.0M for the next couple RFA years. Then become UFA and would sign for what? Depends on how he plays of course, but I don't see him actually developing a whole lot more than what he is right now, but firming up his role as a dependable top 4, with minor offensive upside and good defensive role. So maybe $4M. So, 2 RFA years at $2.0M then 2-3 UFA years at $4M. That would put him at an AAV for 4-5 years around $3-$3.2.
But the player is getting the security of the team betting against any regression.
I don't know maybe my evaluations and analysis is way off.
* Also, he is already 25, leads more to the fact that Zub is what he is, less likely that his progression is going to track upward greatly.