With the emergence of Pierre-Oliver Joseph and with how fantastic Matheson looks, there is definitely a logjam at LD for us. Dumoulin definitely shouldn´t be untouchable like he was one year ago. I would explore trading him or Pettersson. Both are solid solid players but I prefer Matheson and Joseph over them and it also looks like a good asset management to treat it this way. Rust is obviously going nowhere, he has been our BEST PLAYER this season but Dumoulin is interesting to find out.
IMO the Pens have a very underrated and deep defense squad. Matheson is really really playing great now and even Ceci looks rock solid in his role. Joseph is clearly NHL ready and more. Marino is back to form. Letang regressed, that´s obvious but he is still good. Pettersson or Dumoulin, just makes no sense to scratch one of them, they are too good for it. P.O.Joseph needs to play, would be a real shame if he is the one scratched and that´s the reason why we are discussing the value of Dumoulin.