Bylsma's problem was an inability to adapt in game to situations - Sutter does that well, juggling and running the lines that are performing well while not shortening his bench. He only had to shorten it once, and it was against Chicago; even then he was only down his fourth line for one game.
After that things were golden.
Pens were never able to do that, simply because they didn't have the depth. They removed Therrien though because the players clearly weren't responding anymore. That kind of thing happens.
The Pens just need to stop riding Crosby and Malkin because so long as the other team can shut them down... they're not going anywhere. Fleury isn't a good enough goaltender to steal any important games and the defense is shoddy at best; Blue Jackets targeted Scuderi with some success and Orpik doesn't have too many good years left in him. Niskanen is the bright side there.
It'll be interesting to see how they handle next season though.
But no matter what, you've still gotta go through the West