This might not have been the clearest night for a declaration of who the Rangers will be. But it certainly said a lot about who they are not. They are no longer the team that started this season not knowing how to take advantage of defensive lapses, the team that looked defensively lost in the face of a high-powered offenses. All of that stuff was left in the past on Wednesday night at the Garden, when the Rangers beat the East-leading Penguins, 5-1, allowing that early-season dysfunction to be of a seemingly bygone era. “I think our players are anxious for this game,” a calm coach Alain Vigneault said Wednesday morning. “They know Pittsburgh, it’s a divisional game, they know they’re one of the best teams in the NHL, they have some star players that get a lot of attention. So they want to go on the ice and prove they’re good players and a good team. I think everybody is going to be ready.” Everyone was ready, and the Rangers (7-8-0) won their fifth game of the past seven, and ended a four-game winning streak for the Penguins (11-5-0) in grand fashion. The Rangers played with creativity and confidence in the offensive zone, and were stout and poised against Sidney Crosby, Evgeni Malkin, and all the Pittsburgh elites. By the time midway through the third period when Derick Brassad slapped in a loose puck on the doorstep — put there by none other than grinding forward Derek Dorsett — the new scoreboard at the Garden was glaring a 5-1 advantage for the home team. The second period was when the Rangers really ran away with the thing, clamping down and defending a 2-0 lead without being passive. Brian Boyle, a force all night on the penalty kill, was rewarded for his hard work, when he netted his first of the season on a low wrist shot with 13:10 gone by in the period, giving the Blueshirts a 3-0 lead. The Penguins did push back, getting a power-play goal from Kris Letang just 1:24 later, cutting the lead to 3-1. But as if to not allow the dangerous Penguins any chance of momentum, just one more minute went by before Ryan Callahan got his fourth of the season, his stick being on the money end of a double-deflection with Brad Richards, redirecting a Carl Hagelin turnaround shot and giving the Rangers a 4-1 edge.