He's had a rough year.
I'm of the opinion that they won't move him and I don't believe that they'll actually do much of anything to the defense for next year. Fitz has shown he is patient. Can't trade every guy on a down year and Marino and Siegs had down seasons. I suspect that he's going to let each of them show that they can bounce back. Bahl is the only guy that I can see get shipped out to try and improve that third pairing.
Yeah. I don't really see him making huge revisions to the defence either. The whole...letting Graves and Severson walk thing was always a bit of a gamble and a "take a step back to take two steps forward" sort of thing. It was always about not committing to older guys, because there are young players coming, like Nemec and Hughes.
There's a bit of a missing link there though...where it seems pretty doubled up on certain skillsets. Though that probably looks more like you're suggesting...trying to find an upgrade on Bahl as a physical, defensive/matchup sort of presence. Bahl hasn't filled Graves' shoes at all. So that's something that you probably have to figure out to get Marino going again. Heck, they could probably get Graves himself back for not that much if they wanted to.
As far as Severson...i think Nemec has pretty much stepped in and backfilled that. With a year of experience under his belt, i think that's all pretty squared away down the RHD side.
But that's where it probably makes even less sense to move Siegenthaler in a deal, where he may have had a down year (low point in his value) but is still effectively their best defensive-oriented LHD. Where they really need to
add another player like that, rather than subtract one. Unless he's being packaged for a major LHD upgrade...i'm still not sure how that would even look. That value contract he's on seems like an important part of the cap structure anyway.