Nicklas Backstrom is a believer in puck luck, something the Capitals have had plenty of against the Bruins in recent years. Backstrom and his teammates had luck on their side again Thursday night as he scored the third-period winner to help Washington win its 14th straight over the Boston Bruins with a 4-2 victory. “Sometimes hockey isn’t fair,” Backstrom said after the Capitals won despite being outshot 41-22.