For many National Hockey League teams, these are the dog days of winter. The holiday break is over and the second half of the 80-game regular season stretches interminably toward April.

It is a time when the well-disciplined, dedicated Washington Capitals usually feast on less motivated clubs. Last season, for example, they had a 13-2 record in the month following Christmas.

Now, the Capitals are experiencing the doldrums themselves. Since Coach Bryan Murray gave the team a three-day Christmas holiday, Washington has stumbled along at 5-4. Three of the victories were by one goal after early leads slipped away and three of the losses were to sub-.500 teams.

The latest setback, by 5-3 to the Minnesota North Stars Saturday night, dropped the Capitals eight points behind first-place Philadelphia in the Patrick Division, and it became 10 when the Flyers shut out the Calgary Flames last night.

It would be easy to attribute Saturday's result to the goaltending of Minnesota rookie Jon Casey, who stopped 41 attempts as Washington had a 44-25 shooting margin.

The Capitals did manage three goals, two by suddenly sound Bob Carpenter, and seven times this season have won with three or less. It was not enough this time because of some questionable defensive plays that made it easy for the North Stars to whirl in on goaltender Pete Peeters.

"We gave up four goals on dumb plays by our defense.. . . Gambling and giving the puck away," said Murray.

Although the Capitals had nine shots on Casey in the first five minutes, ex-Capital Tim Coulis of the North Stars produced the only goal on a tap-in at the finish of a three-on-two with fellow fourth-liners Dirk Graham and Keith Acton. They whipped the puck around like Gretzky clones against defenders Dwight Schofield and Larry Murphy.

"On three-on-two plays, they should be eliminating the man going to the net," Murray said. "The goaltender has no chance on those tap-ins."

The score became 3-1 late in the second period when Murphy tried to carry the puck out from behind his net and was pulled down by Neal Broten, who shoveled the puck behind him as he fell. It might have been a penalty, but wasn't, and with Peeters caught out of the net by Broten's move, Brian Bellows skated in for an easy goal.

The entire Washington team should have been asked to produce ticket stubs when Graham skated from behind his own net to deposit the puck behind Peeters for a 4-2 lead. Most embarrassed was Peter Andersson, who came closest to touching the Minnesota winger, but was victimized by an outside fake inside the Washington blueline.

The goal that will look worst of all on the videotape ended the Capitals' hopes of a comeback with seven minutes left. It was another three-on-two, with Broten the spearhead and Scott Bjugstad and Dino Ciccarelli on the wings. Both defenders, Scott Stevens and Kevin Hatcher, went after Broten as he skated over the blueline. When Broten got off a pass to Ciccarelli, it created a two-on-nobody and Bjugstad had an easy 25th goal.

"Both guys go for the puck carrier, they're leaning the wrong way and out of the picture," Murray said. "We had the chances to win the game and instead we just give it away."

The other Minnesota goal came on a first-period power play, Bellows providing a screen for Steve Payne. It was the 18th extra-man goal yielded by the Capitals in the last 13 games. Washington's penalty killers gave up only 18 in their first 28 games and ranked No. 1 in the NHL at that point. They have slipped to fifth and given Murray yet another cause for concern.

"We've become very tentative," Murray said. "The way we kill penalties normally is to be aggressive, but we were giving up some goals, and I guess it's made guys a bit cautious. So we're standing back, giving them time to set up and we're giving up even more goals . . . we seem to get our stick on the puck, but we don't get it out over the blueline. We give them a second chance and they finish it. I'm a little concerned about it. Any time you lose a couple of games, you're concerned."

Another area of concern is the flu that has affected some of the Capitals in recent weeks. Although Carpenter left his sickbed in Washington and flew to Minnesota not only to extend his iron-man streak to 361 games but play his best game of the season, illness suddenly forced out Darren Veitch.

Center Alan Haworth, returning from a week's layoff because of a concussion, was shaken up by a last-minute check from Ed Hospodar. However, everybody skated at yesterday's practice except center Bengt Gustafsson, who suffered a pulled leg muscle Saturday. He is expected to be ready for Tuesday's home game against Calgary.

"This time of year, with the travel and the weather, you always have a few guys feeling shaky," Murray said. "You just have to play through it. At least, it hasn't been as bad as last year, when we'd have six or seven sick at one time."