This team wasn't going to contend in 18' and Hjalmarsson's game drops off a cliff if he loses a step since he can't do much in the offensive zone in my opinion. Hammer was one of my favorite Hawks, but I have been dreading what he's going to look like and what he's going to want get paid at the end of his current contract.
My only issue with the return is Murphy's health, he's got to clean up some of the unnecessary/non useful abrasiveness so he stays on the ice and is 100% going into the spring. He skates pretty well imo, I think he will evolve defensively.
I'm pretty upbeat about the trade, I don't think Hjalmarsson is going to be worth nearly as much next summer and I'm not convinced he can help the team win long term at a big cap hit.
If I thought they were in a spot to better contend in 18', this trade might upset me. Given the circumstances, it's a gamble but it's an equal gamble (for me) to bank on Hjalmarsson maintaining his level of play.
Besides, this is much more fun than dumping a player just for cap room.