In terms of philosophy, I actually 100% agree with Sullivan on a few things.
1) The team is at it's best running 4 skilled lines. Run 4 and teams cannot keep up with us. Right now we cannot do that.
2) The best defense is staying in the offensive zone. And that's my argument for that 4th line. Kuhn/Reaves cannot possess the puck and Kuhn's best attributes are exactly what the team doesn't want to get into for an identity - playing defense. So the Pens are at their best when they are attacking and then flying back on transition defense. That makes the opposition dump the puck, change, and we go back at it.
I don't disagree, but I'd say Letang's struggles have way more of an effect on our possession and attack time than Reaves/Kuhn/Rowney/etc sorta doing whatever they do for their 8-10 minutes a game. Letang's coming back from a real serious injury and surgery, so I know there's gonna be an adjustment period and a ton of rust, but he's gotta kick it into gear sooner than later. I touched on it in another thread, but I'm pretty interested in how much of Letang's struggles are rust/timing-based as opposed to him trying to overthink everything because of what Sully and the coaching staff have said to him this summer or asked him to work on with regard to playing a more controlled, safe game. Letang, for his entire career, has struggled mightily with calculated play and doing anything besides playing on pure instinct and athleticism. Once he starts to think about stuff out there, he falls apart. You can see it on the power play--he second-guesses his decisions, he double pumps his passes/shots as he questions himself, he waits a second too long and allows the PKer to get into his lane and fires off a shot right into the guy's shin pads. As much as Letang needs to be healthy and needs to not put himself in desperate, dangerous situations, he also loses a big part of what makes him successful and such an effective player once he starts to overthink things and alters his game. There's no real middle ground for Letang, I think. It's either balls to the wall, reckless abandon or a complete mess, lacking any sort of confidence or flow to his game.
Sheary's a shit-show defensively, and it really f***s with Sid's line. Sheary's got some really nice skill and speed, and he has been showing it, but whenever he's asked to do anything without the puck on his blade it's rough. Puts way more pressure on Sid and Jake to do "too much" so to speak. Geno and Kessel have struggled defensively as well, particularly Phil--though he made a great play to break up the pass and go the other way for his 2nd OT goal the other night. The third line is gonna be touch-and-go for a while until we sort of figure out what Sheahan is capable of and how he's gonna fit, but I've been pleasantly surprised with his play and the way the line has performed so far. The fourth line is a pretty big mess for reasons you, I and a dozen other people have outlined many times. Kuhn's a solid 13th forward, but probably shouldn't see every day time. Reaves is playing a lot more like the guy we hoped he wouldn't be as opposed to the guy several people said he would be. But again, losing Cullen decimates that line and it's effectiveness, and there's really no way to replace that dynamic.