Washington has gone 1 for 27 on the power play over the past eight games. (Tom Pennington/Getty Images)

DALLAS — There’s traditionally a cardinal rule for when playing the Washington Capitals: stay out of the penalty box.

The Capitals have had the most effective power-play unit of the past decade, a fact that opposing teams are well aware of. But in the final 10 minutes of a tied third period Friday night, the Dallas Stars broke the cardinal rule twice, and Washington had two of its best-looking man-advantages of the past three weeks. It still didn’t score and eventually lost the game in overtime.

The Capitals are 1 for 27 on the power play over the past eight games, and though they didn’t score in three opportunities in Dallas on Friday, the improved zone time and entries left Washington at least encouraged considering how the unit has scuffled of late. As the team’s five-on-five offense has dried up during this three-game losing streak, the Capitals’ first of the season, the power play’s struggles have grown more frustrating, no longer a reliable source of scoring.

“Almost every year we have that kind of break when we felt like maybe we just have to change something,” captain Alex Ovechkin said. “We don’t have to change anything because we top in the league if we play right way, if we play smart, if we do the right things.”

Ovechkin’s right, and while Washington’s 1-3-1 format is certainly predictable, it has a track record of success. The Capitals had a 1-for-27 stretch around this time two years ago, and they still finished with a top-five scoring percentage. Washington is ranked 10th in the NHL with a 22.1 percent conversion rate, and that’s buoyed by its hot start. In the Capitals’ first 10 games, they scored 13 goals on 35 power plays, an unsustainable 37.1 percent.

“If you look at the start, I thought it was almost too good to be true,” center Nicklas Backstrom said. “We’d score on everything. You’re going to have dips, and it’s going to go up and down. But one thing we’ve got to realize is that we’ve got to work even harder on the power play to create these chances and make sure we stay on top of those guys.”

The strength of the Capitals’ power play is in its variety: If a team’s focus is on taking away Ovechkin’s one-timer from the left faceoff circle, forward T.J. Oshie might be open in front of the net or defenseman John Carlson at the point. But as opponents have employed more in-zone pressure during penalty kills, the Capitals have struggled with their zone entries. And even when they’ve gotten set up long enough for a good shot, they’ve often lost possession right after that, wasting valuable time and energy retrieving the puck and starting all over again. At its best, Washington can get into its formation and create a quality scoring chance through extended possession and puck movement.

“That’s all we talk about,” Backstrom said. “You’ve got to get zone time, you’ve got to move the puck, and you’ve got to come up with things to break down other teams.”

Washington’s top unit tends to stay on the ice for roughly 80 seconds of a two-minute power play, and while that group has stayed intact, Coach Todd Reirden made changes to his second unit against Dallas: Right wing Tom Wilson and center Travis Boyd replaced Brett Connolly and Lars Eller. Reirden said part of his thinking was spreading out the ice time with the Capitals playing their second game in as many nights.

“We’re just trying to get back to giving players opportunities, giving them opportunities in situations and going with some different guys,” Reirden said. “Sometimes when you don’t have a ton of success — and for us, the majority of our ice time is spread out with our first group, so maybe not a completely full evaluation with our second group — we wanted to look at some different things and give some different people an opportunity.”

The one power-play goal the Capitals scored during this eight-game stretch was a tip by Oshie in front of the net against Carolina, Carlson’s shot glancing off Oshie’s blade and into the net. “When you can’t find a way to score when you have that much level of talent on a unit, you sometimes have to simplify things,” Oshie said that night. Just as it does now, the power play seemed to be on the cusp of breaking through then, feared by any team that dares to take a penalty against Washington.

“I’m not worried about it,” Ovechkin said. “We’re going to be fine.”

Reirden to coach in All-Star Game

With the Capitals boasting the best points percentage (.650) in the Metropolitan Division at the NHL’s halfway point, Reirden will coach the Metropolitan team at the All-Star Game in San Jose this month, an impressive honor for the first-year coach. Tampa Bay’s Jon Cooper, Calgary’s Bill Peters and Winnipeg’s Paul Maurice will be the other coaches.

Reirden will be joined by goaltender Braden Holtby and Carlson as the Washington representatives. Backstrom, who has 10 goals and 34 assists, could be voted in for the last spot on the Metropolitan team. This is the third time in the past five years that the Capitals' coach has been at the All-Star Game.

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