The Flyers had gone through the series-capping handshake line and now were milling about the Wells Fargo Center rink with their sticks raised, an acknowledgement to the applause from the fans who remained, and as the players started filing into the locker room, Sean Couturier was by himself for a while at center ice. He was with his teammates but apart from them, too, just as he had been over these final two games of the Flyers’ Eastern Conference quarterfinal series against the Penguins. The winning goal in Game 5, a remarkable three goals and two assists Sunday in a wild 8-5, season-ending loss in Game 6 – all of it with a torn medical collateral ligament in his right knee, all of it necessary for the Flyers to make this series competitive again.