DeSmith actually stepped up and stole that Avs game. But that is a once-in-a-blue-moon kind of performance from him. We'll need more like that if the Pens are to get to the post-season.
All the things you listed are spot on, plus the fact that the bottom 6 forwards contribute virtually nothing on offense. Carter is a shell of the guy we traded for two years ago, and Kapanen, Heinen, McGinn, Blueger are all having subpar years. And unfortunately we can't play Crosby's and Malkin's lines for the entire game. People bang on the Pens as an 'old' team, yeah, but the 'old' guys (minus Carter) are the ones carrying the team.
The penalty kill is better with Teddy B on the ice but the rest of the guys you mentioned absolutely stink this year. I loved the Carter trade two years ago. What a beast he was. But holy cow. What happened to that guy. Every facebook post after a loss is comments of 'shouldn't have kept the core together'....which I just don't get. Aside from Letang's horrendous start to the season, those three aren't the problem. Malkin is playing great hockey lately and Crosby continues to do what he's always done, perhaps not at the level of previous years but my goodness. Plus, where was the team when Anderson cross checked him? No grit from anyone on that team.

