The sad reality is that you can't 'trade' or 'UFA' your way to competent blueline in today's NHL. And even finding 'depth guys' is going to cost you valuable picks and prospects.
Look at the cost of acquiring Zadorov late last season as a pure rental. It was a least a first round pick; an top prospect; and some late round picks. Although they did manage to dump Kuzmenko's contract.
Is Zadorov a top four guy? Well even that's debatable. A legit top four guy is going to cost you the farm, even if one was available.
So the only options Allvin has every off-season is signing another bunch of marginal guys as UFA's. I mean look at this group. Forbort barely got on the ice in Boston last season; Desharnais wore out his welcome in Edmonton and has been scratched at least 10 times; Juulsen at his best is an AHL-NHL 'tweener; and Myers, well he's Tyler Myers. Now 34 he just can't play top minutes any more. And Brannstrom came in via the waiver wire and is now gone.
And of course Soucy, who was decent last season as an incoming UFA, has seen his game basically implode this season.
I mean outside of Hughes and Hronek, the blueline depth is a disaster. The reason of course is that outside Hughes, they have drafted a single competent d-man.
But at least there's help on the horizon with Wilander, D-Petey, and maybe Mynio and Kudryavtsev. But in fixing the blueline once and for all--patience is the only option they've got.