If the Rangers are able to "fire on all cylinders" throughout the playoffs they will win the cup without a doubt. I don't think any series goes past 6 games in that case.
The problem is, teams VERY rarely do. The only team that I can think of that did it recently is the cup winning Kings. They were at legitimately good team (top-5 in the league) that underperformed in the reg. season and "fired on all cylinders" throughout the playoffs absolutely steamrolling everything.
Think about what that would mean for the Rangers: Nash and MSL scoring at PPG. Stepan, Zuccarello, and Richards just below. Hagelin, Brassard, Pouliot, and McDonagh just above 0.5 PPG. Hank puts up 93%. Our possession game runs at 55-60%. No team in the league (unless they are also firing on all cylinders, and then only a few) can stand against that over a 7 game series.
We have enough depth to handle a disappearing act or two. Arguably we can handle more disappearing acts than most teams. But it's tough when our most prolific scorers are the ones disappearing.
I've been a big proponent of this team and I still think we can go far, but not playing the way we have been for the past ~15 games. Sure our record is good, but our possession game has dropped off significantly and our best players haven't been playing near their potential.
This is a good team at it's core, but it needs to start playing like one again if we want to contend.