When people talk about “breakout” players, Dunn was already a known commodity, but I felt like he was going to break out even more. He’s had a great season, especially from an analytics perspective, but his ice time has dropped 1:16 per game from last season (17:32 to 16:16). You can look at this two ways: He’s having success because he’s playing third-pair minutes against less talented forwards or he’s playing well, so play him more.
I understand that Faulk is a three-time All-Star who can play 20 minutes per game, but I would play Dunn in the top four before I would have one of the right shots playing on his offside. Dunn has had chances in the top four and made some mistakes, but he’s a better player now and deserves a longer look.
Finally, to answer your question about Dunn being expendable, my answer is no way. He’s a 23-year-old who’s as good a skater as you’ll find on the back end, can quarterback the power play, is pretty solid defensively and is cheap. He’ll be a restricted free agent without arbitration rights. Yes, the Blues have Scandella locked up for four years and Niko Mikkola and Perunovich on the way, and don’t forget about Jake Walman, but none of them are where Dunn is right now. To me, he’s not expendable.