According to Adam Gretz of NBC Sports, Couturier revealed he tallied a hat trick in Sunday's 8-5 loss—which gave Pittsburgh the 4-2 series win—all while playing with a torn MCL. John Boruk of NBC Sports Philadelphia reported the injury would have kept Couturier out for at least four weeks had it been the regular season.
Gretz noted Couturier missed Philadelphia's 5-0 loss in Game 4 with the injury after he collided with teammate Radko Gudas during practice.
Couturier also had two assists in Sunday's loss, meaning he was a direct factor in each of Philadelphia's five goals after he tallied the winning goal in the third period of Game 5.
During the regular season, the NHL named Couturier as one of the three finalists for the Frank J. Selke Trophy, which is given to the forward who is best on the defensive side of the ice. Patrice Bergeron of the Boston Bruins and Anze Kopitar of the Los Angeles Kings were also finalists.
Couturier was durable throughout the season and played all 82 games. He tallied career-best marks nearly across the board with 76 points on 31 goals and 45 assists and was also a plus-34, per ESPN.com.