No, I'm not misconstruing you saying he is good- and no, I'm not making any argument from emotion- but thanks for assuming that. My assessment is based on his metrics and analytics over the past 3 years. Knoblauch clearly sees it too because he started playing Nurse as a third pair. I can get into his xGAR%. Transition defense, rush chances against, successful zone exits- but I wont here. Bottom line- this is exactly who he is. Him and Ceci were outscored 15-3 against Colorado and Vegas the last 2 playoff season- the trend is continuing. His performance this year shouldn't be surprising to anyone.
What I've said if you paid attention is that he is not playing his game anymore. He is not skating, joining the rush, contributing offense 5-on-5 as well as munching big minutes.
Therefore I suspect there's something hampering him physically this year similar to how he was hampered physically against the Avs (which you conveniently omitted).
Maybe it's just a confidence issue from being passed on the depth chart but Darnell doesn't strike me as a guy who is very down on himself.
Maybe with age and starting a family etc he doesn't have the same swagger anymore as some have alluded to.
He was never as good as that contract but he clearly looks off this year compared to previously. We see it with Connor too, although Connor obviously is a much better player.