On some of the above:
I think that the issue comes down to not only the left/right side thing, but also the O from the D thing. Methot, Gryba, Cowen, and Phillips: I love that quartet in front of my goalie, but I'm less enthused at the prospect of trying to ice 2 PP units with them being 4 of the only 6 D options we have.
BM has had a long-standing policy of trying to get a little O out of every D pairing -- he's been saying that since he passed on Volchenkov and signed Gonchar. For that reason, I think they look for another right side D who brings more offense to the table. It's also why I think moving Wiercioch would be a tough pill to swallow -- if you lose Gonchar, literally only he and Karlsson bring any real creativity and offense.
This would be a whole lot easier if we had one forward on our team who could consistently play the point on the PP.