Why not just buy Johansson for a third or something? I think Pens should keep Pettersson, and SEA is probably looking to change the likes of Soucy for futures too, considering how bad their first year has been.

I wanted to move a LD from Pittsburgh, Pettersson has a longer contract that we don't need, Soucy's contract will expire when Joseph should be ready for NHL. I also wanted to add players which are harder to play against. I don't see any reason why Pettersson shoud be an issue for Seattle.

Well he's not exactly an issue, but the reason why they'd not take him in is exactly the same why you'd move him - it'd cause a logjam of LHDs there. Giordano, Dunn, Oleksiak, Pettersson/Soucy, Lauzon, Fleury. All of them are LHDs and in need of NHL time. In this regard it would make sense for them to deal a LHD for prospects, and since aside from Giordano and Soucy all of them are either young LHDs themselves or extended long-term they are the most logical options to move.

That's a fair point, but Giordano will surely be traded, Lauzon also plays RD, and I don't know how much they trust Fleury to be in a permanent spot.

Yes, most likely. Point is that I don't see much need for trading for other LHDs seeing how "stacked" they are.