I think almost every team in almost every professional league (other than the NFL who play only 17 times + playoffs) falls into this category. When you have so many games it's impossible not to have peaks and valleys of effort and urgency.
Maybe the Rangers fall into this category a little more than others, part of me thinks it has to do with the way they are "spoiled" by the franchise with the many perks that come with being a Ranger/ living in such a unique metropolis with more distractions and attention. I also think certain upper management has an air about them that contributes to this...
Plus, as NY fans I think we are harder on our teams more so than in other cities and areas, so we always attack the passion or urgency level of the team because we live in such a fast paced dog eat dog environment.
Some teams may do a better job of managing it better, but sooner or later the talent levels catches up in the big games - as Inferno mentioned.
All things being equal, I don't think it's entirely fair to label the Rangers team this way.