The Washington Diplomat defense totally collapsed today.

Playing as if they were knee-deep in muck, the Diplomats stood and watched the Chicago Sting ring up five goals, three by Arno Steffenhagen, and administer them a 5-2 shellacking before 18,226 at Wrigley Field.

Undaunted by a 28-minute rain delay the Sting, American Conference Central Division leader (11-3), burned the slow-reacting visitors for four second-half goals. Steffenhagen scored two within a four-minute span.

Outshot by a whopping 26-14, Chicago made the most of every big scoring opportunity.

"The second half was like the St. Valentine's Day massacre," Washington's Carmine Marcantonic said in an apt Chicago analogy.

Washington (4-8) was without Johan Cruyff, home nursing a pulled thigh muscle, and Joe Horvath, hit with a two-game suspension by the league Friday for his altercation with official Gordon Arrowsmith in last Sunday's game against the Cosmos.

It is doubtful even those players would have made much difference. Worse, the Dips may have lost two other midfielders. Sonny Askew hurt a foot and will be examined for a possible fracture. Juan Jose Lozano was kicked in the calf. Both players left the game in the second half.

Steffenhagen, who scored 12 points in earning selection as the Sting's player of the month of May, put in an early bid for the June award.

With the score 1-1, midfielder Steffenhagen controlled a loose ball following a free kick and zipped it past a statuelike Washington defense for a 2-1 advantage at 52:48.

"The ball was blocked by him and no one picked him up," Washington keeper Bill Irwin remarked. "I didn't get any help on that play."

Defenseman Tommy O'Hara agreed: "We stood there maybe 10 seconds while he was all alone with the ball. That goal killed us. After that, we fell apart."

With Lozano stretched out on the field after being kicked, Steffenhagen knocked in his third goal of the game. He took a pass from Rudy Glenn, walked around Irwin and pushed the goal home for a 3-1 Sting lead at 56:22. Lozano was being tended to on the sideline by trainer Steve Horner; eventually he would be replaced by Gary Darrell.

"We had much better chances in the second half," said Steffenhagen, who scored his first hat trick since coming into the league three years ago. "Washington's defense didn't react as quick as it did before the rain. After I scored those two goals, they were done."

Washington Coach Gordon Bradley said, "The defense was indeed flat. We allowed Chicago to penetrate and didn't cover. The weather didn't affect us that much. Both teams had enough chances to score."

Satisfied with his afternoon's work, Steffenhagen thereafter took a back seat as his teammates mopped up. Again the Dips stood back as Peter Ressel slowly worked his way into the Washington box. Ressel waited until Jorgen Kristensen streaked upfield behind the defense, then sent him a perfect cross and the winger's header caught Irwin by surprise. The Sting lead was now 4-1.

The Sting's biggest crowd of the year, and fourth largest in the six years of the club, was ecstatic when Ingo Peter curled a 22-yard shot just inside the post.

"Once Arno got us started, we just started cooking offensively," said Chicago Coach Willy Roy, who has the club off to its best start ever. "In the first half, we made long runs and penetrated but didn't score."

Actually, Chicago took a 1-0 lead in the first half. After the rain delay, which left the field a quagmire, Steffenhagen punched a goal over the head of Irwin.

Washington defender Robert Iarusci matched that with 94 seconds gone in the second half. It was Iarusci's third goal in his last three games.

Then the roof fell in on the Dips.

Most of the crowd had long departed when Alan Green scored his 10th goal of the Diplomat season with five seconds left. It was academic.