I don't think it's necessarily obvious Miller was the worst defender last night. Maybe your eye test says that but he looked ok to me and while advanced stats aren't everything the XG% for Nemec and Siege at 5 x 5 SVA was abysmal even though to my eyes Nemec looked pretty good overall. I thought Marino looked shaky in his decision making at times as well. Compared to Smith, I think Miller has looked much better overall. I don't expect him to be better than Luke or Nemec or Marino but there is no reason he can't play on a level reasonably similar to Siegs and Bahl. Hamilton as you've noted is a whole different issue but the team likely won't cross that bridge until next season.We've been asking Luke to do way too much heavy lifting on his defense pairs. First he's saddled with Brendan Smith, then Colin Miller (better than Smith but still our worse dman on the roster last night). Now with Siegs struggling a bit, I don't want to do that to Nemec.
Maybe Luke - Nemec should be tried sooner than later. I know they are both rookies but they are arguably our best dmen already.
Hughes - Nemec
Bahl - Marino
Siegs - Miller