I really do feel that, in terms of raw ability, Blake has done a great job getting a good mix of dmen, offensive and defensive.
The real problem is most of those guys are below average size and as such it may mean moving a smaller guy with good ability for a bigger guy with 'lesser' ability.
Bjornfot and Spence cannot be an NHL pairing. They're both skilled enough but they would get absolutely ruined night after night. You can even see that when it's Bjornfot/Roy. You can't have an entire smallish 6ft and under blueline. And I don't even say that from just a raw physicality standpoint--speed and power are skills too.
At some point in the next couple of years, we have to kiss goodbye to one or several of Walker, Bjornfot, Spence, Durzi, Kim. N. Even Roy is borderline but if he's the smallest one or 2nd smallest, I think we're okay. Now obviously it's more nuanced than that but you get the point.