Through four games under new coach Adam Oates, the Capitals were leading the league in power-play goals allowed and in most times caught short-handed on the ice because the team is taking too many penalties. (Jonathan Newton/The Washington Post)

The moment the referee raised his arm in the middle of a Washington Capitals penalty kill Friday night, disappointment surged through Jay Beagle. He had been whistled for tripping New Jersey Devils forward Travis Zajac and was headed to the penalty box. The infraction put Washington down two men and paved the way for an easy Devils goal.

“We’re halfway through killing that off and I take a stupid penalty and put our team down. It doesn’t feel good,” Beagle said. “You can’t let them have five-on-threes in this league. You’re out there do to a job on the five-on-four, you definitely can’t take a tripping penalty.”

Beagle has hardly been the only culprit. Frequent penalties have become an undesirable trend of the Capitals four games into the season.

Heading into Sunday’s matinee with the Buffalo Sabres at Verizon Center, Washington has been whistled for 25 minor penalties with no less than five in any game. The infractions often arrive in bunches, stifling momentum, sapping penalty-killers’ energy and stemming the flow of the game.

It’s generally accepted that referees tend to call more penalties at the beginning of the season, but the Capitals know they must inject more discipline in their game to avoid making themselves vulnerable.

“We need to be smarter,” said Mike Green, who is averaging 3 minutes 12 seconds of short-handed ice time per game. “The penalties we’ve [taken], have been legit. We need to keep our mouth shut and, also, enough flicking pucks over the glass when we already have a penalty to go down five-on-three. So just got to be smarter.”

Only seven skaters on the roster — Marcus Johansson, Eric Fehr, Karl Alzner, Tom Poti, Roman Hamrlik, John Erskine and Jeff Schultz — haven’t been penalized.

Of the 25 minors, nine were offensive-zone penalties, three were delay-of-game calls for firing the puck over the glass, two were for yapping at officials and three came while the Capitals were already short-handed to give an opponent a five-on-three. And far too many have been needless.

“When you’re taking holding penalties and tripping penalties behind their net, those aren’t good penalties,” said forward Troy Brouwer, who was guilty of firing the puck over the glass to give Montreal a two-man advantage on Jan. 24 and negated a power play against Winnipeg on Jan. 22 when he was whistled for interference in the offensive zone.

“If you’re on a back-check preventing a goal or preventing a good opportunity, we’ll take those,” Brouwer added. “Where you go finish your check and maybe get your hands a little high or something, those are all right. . . . It’s those lazy penalties or unnecessary penalties where there’s no chance for them to even score a goal that really deflates guys.”

Prior to the conclusion of Saturday’s games, no team had allowed more power-play goals (eight) or been short-handed more times (24) than Washington. With a penalty kill that is trying to find its footing and effective only 66.7 percent of the time (18 of 24), the Capitals simply can’t afford to spend large chunks of ice time short-handed.

It’s a simple corollary, veteran center Mike Ribeiro said.

“If you’re in the box two, three times a game, I think it’s normal. If you go to four, five, six, then your odds go [up] that they might score a goal on the power play,” Ribeiro said. “You reduce your penalties, be more disciplined [and] obviously, PK will get better by giving two or three a game instead of five or six.”

In Friday’s 3-2 overtime loss to New Jersey, four of the Capitals’ six minors came in the second period — three in a span of less than four minutes. That type of never-ending penalty kill exhausts the players tasked with fending it off and leaves others on the bench, unable to maintain their involvement in the game.

“It definitely doesn’t help, especially when they’re all grouped together like that,” said Alzner, who is averaging 4:46 of short-handed ice time per game. “It hurts quite a bit. It seems like a lot of them have come in the second period, too. It’s been killing any momentum we brought over from the first. Our firsts have been decent and then we kind of shoot ourselves in the foot there not only physically but mentally. I’s not good for us.”