Considering their cap position, perhaps an overpay.

Unnecessary move for Pittsburgh. Take away the leading PK forward and a 2nd (that could be used for a winger trade later) and add to an already too deep D pile. Don't like it.

I am not trading a 2nd? Not sure where you saw that...
Anyways, this was my thought behind it.
POJ seems to be on the outside looking in and I am scared he ends up on waivers. In this case, we at least get a return for him, and I believe Hague is an upgrade. This would mean that Smith would be in the AHL, but if any injuries happen, I think he would be the first one in. Also, Dumoulin's contract is up after this season, so I think the LHD next year would be Hague, Pettersson and Smith.
I do think Blueger is really good, but I doubt we re-sign him because he will demand too much and we have internal options to replace him, even though I would love to keep him. He was also part of the original package we offered MTL for Petry, which was him and Pettersson. I am sure we were willing to move him because management felt like we could replace him internally either with Poehling or O'Connor, or we could promote Poulin to 3C and move Carter to the 4th line.