While the Islanders recorded a 3-1 win over the Capitals on Monday night, the victory may have been even bigger because they did not allow a goal on the penalty kill. It snapped a streak of seven straight games in which the Islanders’ opponents had at least one power-play goal. Opponents had a combined 11 power-play goals in that span. “We hadn’t gotten many results with the penalty kill lately, so good job sticking with it,” John Tavares said. “We looked at it as another opportunity to change the narrative.” Coach Doug Weight dedicated practice Friday in Boston to the penalty kill, knowing it was time “to tinker with some things and to just get a breath of fresh air from our team,” he said. The Islanders allowed a power-play goal to the Bruins on Saturday night, but after Monday, they believe they have turned the corner heading into a Wednesday game against the Stars at Barclays Center.