The Washington Diplomats erupted for three second-half goals and a Jim Steele-led revamped defense put the shackles on the hapless Tulsa Roughnecks for a 4-0 triumph in their North American Soccer League game before 6,696 last night at RFK Stadium.

The Dips' victory, their seventh in eight games, gave them the maximum nine points and boosted them into first place head of the Cosmos in the National Conference's Eastern Division. Washington has a league-high 57 points, eight more than the Cosmos, who play at Colorado today.

A second-half downpour didn't dampen Washington's enthusiasm. Thanks to some shoddy play by Tulsa, the Dips broke one club record and tied two.

Washington goalie Bill Irwin, who ranked second in the league with a goals-against average of 0.56, coming into this game, tied a club record of five shutouts in one season.

"Not bad, huh," said Irwin, who has 44 saves. "I didn't know anything about any record."

Dips' striker Paul Cannell said he wasn't aware he had tied a team record with three assists in one game.

"Had I known, I would've got another," said the flamboyant Cannell. "I just felt like scoring out there. All they did was try to kick us."

Most of Washington's well-aimed kicks resulted in goals. Mike Bakic's first-half goal, at 39:40, came when Cannell hustled over and played an out-of-bounds ball before the Roughnecks had set up on defense. Cannell's high toss was played by Sakib Viteskic, who managed to kick the ball just under the dive of Roughneck goalkeeper Colin Boulton to the right of the net.

While Boulton lay on the ground, Bakic streaked over and easily tapped the ball in from seven yards out.

Tulsa Coach Bill Foulkes said his team was well aware of Washington's defensive problems. Mike Dillon, sitting out a 28-day suspension, and Tommy O'Hara (bruised tailbone) were replaced by ALex Pringle and Randy Garber, the latter seeing his first action of the year.

"We knew it. We just made stupid mistakes," said Foulkes. "We lost our way in the second half. Then just showed a bit more determination and hustle than we did."

Tulsa, only 4.5 on the season but still atop the Central Division, was not in the game the second half.

Bakic scored his fourth goal of the season after Cannell passed to Ray Graydon and Graydon passed to Bakic. His 15-footer was a slow-roller that Boulton, out of position, failed to reach!

Holding a comfortable 2-0 lead with 35 minutes to play, Washington's defense settled down and limited the visitors to a few wild shots. Tulsa's front line of Jim Redfern, former Dips forward, Ninoslav Zec, Brian Smith and Bill Sautter managed only seven shots.

"i was surprised. We didn't have any problems back there (on defense), said Steele, who made several fine plays. "I talked a lot to them and encouraged them if something was wrong. I couldn't believe Tulsa played so bad. Thet were much better the first time (Washington won, 2-1, in Tulsa)."

The Roughnecks were beaten when the score reached 2-0. But the Dips were looking for more.

Sakib Viteskic took a soft pass from Cannell and slipped a low liner under the frustrated Boulton to put the Dips ahead, 3-0, at the 77:56 mark.

The final goal was all Cannell, although Viteskic was given an assist Cannell outran several Tulsa defenders down the center of the field and uncorked a hard shot that Boulton could only marvel at as the ball hit the back of net.

Channell, who has six goals and four assists for a teamhigh 16 points, also got his fourth yellow card of the season late in the first half.

One more card and Cannell will be suspended one game, as will midfielder Carmine Marcantonio, who has four yellows.