Ottawa wasn't a bad team last year. Goaltending was good. EK was amazing. They had pretty good depth up front with balanced lines and probably most importantly they had a lot of things to rally around during the year that built character. They deserved to be in the playoffs.
But i don't think their run in the playoffs was as magical as some people made it out to be.
Boston was injured on the back-end, a team that 100% healthy was probably evenly matched
Rangers pissed away leads in Ottawa in embarrassing fashion, and they were mediocre leading up to the playoffs
Pens were mentally drained from the Caps 7 game series that i thought was evident in the first 3 games, they only scored 3 goals in those 3 games and even got blown out in one of them, then they woke up and scored like 15 goals in the next 4 games, so yeah i don't think the Pens were playing to their level at the start which ultimately played a big part in the series going to 7
Simply put i don't think Ottawa were this amazing team in the playoffs. They were mentally strong for the most part and battled hard, but i don't think any of their opponents were that great in any of their series, and i don't think teams in the East were that great in the playoffs. I think Washington would've beaten Ottawa pretty easily - unlike vs Pittsburgh they have great confidence and swagger against Ottawa and looked evenly matched against the Pens to say the least.
If you ask me this year the East looks a lot better at the start of the playoffs. I don't think last years Ottawa would even get to the ECF.
But yeah as far as this years collapse i don't know what exactly happened. They looked fine at the start of the year but then it just all fell apart after the Duchene trade.