Last spring, in an effort to prevent the New York Islanders from keying on scoring stars Bob Carpenter and Mike Gartner, Coach Bryan Murray assigned them to different lines for the first round of the Stanley Cup hockey playoffs.

The result was disappointing. The Capitals made only 12 goals in five games, although the principal reason for their early demise seemed to be the effectiveness of Islanders goalie Bill Smith and not the shortcomings of Murray's strategy.

When the playoff battle of wits resumes in April, Murray should have no need to worry about opposing checkers shutting down his main point men. Instead, the Capitals boast balanced scoring that is exceptional, with the top five separated by only two points.

Dave Christian and Mike Gartner have 43 points apiece; Alan Haworth, Craig Laughlin and Bengt Gustafsson have 41. In all cases except Gartner, the players seem to be headed for career seasons, and they represent three different lines.

"What we've been looking at for several years is to get to the point where one checking line couldn't offset our strength, and also where we could play a line other than a checking line against an opponent's top line," Murray said.

"We used to have two scoring lines and two checking lines. Although the (Glen) Currie line, our best checking line, forced a lot of play in the other end, it never finished (scored). Now the old attitude is still there toward defense, but we know we can finish some of those chances.

"I wouldn't hesitate to put Bobby's (Carpenter's) line or Gus's (Gustafsson's) line against any of the top lines in the league. And the fact that Haworth's line is playing as good or better than most of the first and second lines in the league gives us an extra dimension.

"That's our only set line, Alan with Locker (Laughlin) and Greg Adams. I've been fooling around with the left wing for Gus and Christian, and the left wing for Carpenter and Gartner."

The "set" line will have a new center for a night when the Capitals face Detroit tonight at Capital Centre, however. Haworth suffered a concussion when he was elbowed by New Jersey's Bob Lorimer Saturday and will watch from the stands while Bob Gould skates between Adams and Laughlin.

Haworth reported to Capital Centre for yesterday's practice, but he still was shaky, his stomach was too upset to handle food and his face was still healing from effects of both the elbow and the subsequent scraping when he fell to the ice.

This is Haworth's sixth NHL season and his 19 goals and 41 points already are close to his peak one-season figures of 24 and 55, in 1983-84 with the Capitals.

"This is the best he's ever played," Murray said. "Playing center is a tremendous advantage for him. He's physically involved and his shooting is more accurate than before. He feeds off his linemates as they feed off his speed."

Laughlin, with 12 goals and 29 assists, also figures in his fifth NHL season to outdistance his best one-season mark of 52 points.

"We look at Locker at the start of each season and figure him for a third- or fourth-line guy," Murray said. "But he has good hands, he's very creative, he shoots the puck a ton and he's willing to pay the price. He's also a smart player. If we put something (new) in the system, he's one of the first to pick it up."

Christian's past peaks were 29 goals and 81 points. In his sixth NHL season, he already has 23 goals and 20 assists, with an amazing 13 power play goals.

Gustafsson is unlikely to match his NHL high of 32 goals, reached two years ago, but he should better his 43 assists and 75 points. His figures in his seventh season are 12 goals, 29 assists.

Gartner, 22 goals and 21 assists in his seventh season, is a bit behind last year's breakthrough 50-52.

"His speed and work ethic have been there throughout," Murray said. " . . . He's going to score. We all know that." Canadiens 9, Blues 2: In Montreal last night, Kjell Dahlin marked his selection yesterday as NHL rookie of the month for December by scoring his first hat trick in the rout of St. Louis. Montreal scored the game's last six goals and took first place alone in the Adams Division. Penguins 4, Devils 3: Pittsburgh's Terry Ruskowski scored from a scramble with 1:37 left in the third period to provide a home-ice victory and extend New Jersey's losing streak to eight games.