The Rangers are being coached, and have been for a while, as if every game were a playoff game. After an atrocious start to the season, it’s hard to dispute the necessity of that mentality as purveyed by Alain Vigneault. But it’s equally as hard to think that such urgency is sustainable, being that it’s also antithetical to the way Vigneault says he wants to manage his roster. That begins with Vigneault saying he wants to roll four lines, though that sentiment hasn’t been executed. Because why then was Rick Nash sitting for the final 9:12 of regulation on Tuesday night against the Penguins? Say what you will about Nash’s offensive production — although saying he isn’t due for an offensive outburst would be shortsighted — but he is undoubtedly one of the Rangers’ best defensive forwards. And there he was on the bench, next to linemates Kevin Hayes and Jimmy Vesey, as the fourth line of Boo Nieves, Paul Carey and Jesper Fast got regular shifts while successfully defending a one-goal lead that turned into a 4-3 victory over the two-time defending Stanley Cup champions. So it’s good news for the Rangers they have a productive and dependable fourth line, especially as they prepare for Friday night’s match in Washington that kicks off a stretch of six games in nine nights that will necessitate depth, from top to bottom.