This evening, before a sparse Memorial Stadium crowd of 8,040 that was too stunned and disheartened even to boo, the Baltimore Orioles did everything conceivable to lose a late-inning lead and present the Seattle Mariners with a 4-3 victory.

"That would have been a great game to win," muttered disgusted General Manager Hank Peters, "and it's a real bad game to blow."

A victory would have given the Orioles an acceptable 7-4 home stand after their horrid 2-9 season's start. And they could have started an 11-game West Coast road trip with the impetus of a three-game winning streak.

Instead, the Orioles will fly out demoralized, showing signs of internal divisions, and with the fresh memory of perhaps the ugliest defeat of what has been a brutally homely 8-14 season.

The Orioles entered the ninth inning with a 3-2 lead and Sammy Stewart, who had squelched an eighth inning Mariners rally, on the mound. However, looming in the background was the fact that Stewart had thrown 128 pitches on Saturday. He was on the mound with just two days' rest only because Manager Earl Weaver has little confidence in his bullpen.

With one out, Stewart allowed line singles to left by Todd Cruz and Joe Simpson. After a line out to right, Stewart gave up a game-tying line single to center by No. 9 hitter Jim Essian. So humble are the Mariners that they didn't even send up a southpaw pinch hitter against Stewart, letting Essian bat for himself.

That's when the horrors started. Three times this night, Orioles outfielders had timidly let liners fall in front of them. This time, Al Bumbry decided to gamble when, as it proved, he couldn't get within four feet of making a shoestring catch.

The liner bounced off his shin and rolled 20 feet. When he tried to grab the nearly stationary ball, he booted it again. By the time Bumbry had reversed his field, grabbed the ball, ignored the cutoff man (an Orioles trademark for two years) and thrown wildly in the direction of nobody in particular, Simpson had slid home with the winning run.

That crime against Orioles fundamentals simply capped a night of exasperation. The Orioles took a 3-0 lead against starter Gene Nelson (1-4) on John Lowenstein's solo homer in the second, and Rich Dauer's RBI double to right and Ken Singleton's RBI single to center in the two-run third.

Nelson looked like a slop-tossing goner. Instead, as Weaver said, "he settled down and we never got another smell (of him)." After allowing a two-out walk in the ninth, Nelson needed relief help from Ed Vandeberg, who struck out Bennie Ayala.

Slowly, and exasperatingly, the Orioles' lead disappeared. In the fifth, Steve Stroughter, with one career single to his credit, hit an opposite field fly to left that grazed the foul pole 309 feet away for a homer. Stroughter sprinted all the way to third, ignoring the umpire's homer signal as if he'd never seen one. "I was goin' for three (bases) . . . I thought the umpire was kidding me," said the rookie.

In the eighth, the Mariners got another run. After a leadoff single, Essian hit a slow chop to third-baseman-for-a-night Fat Floyd Rayford. Essian then slipped and fell in the batter's box. Rayford, incorrectly assuming no double play was possible, flipped a very soft toss to second, which allowed Dauer to be taken out by the sliding runner while Essian was still 40 feet from first.

A gift turned into a run as Julio Cruz walked and Bruce Bochte singled (kayoing starter Dennis Martinez), bringing Essian home to cut the Orioles' lead to 3-2.

"Dennis pitched 7 1/3 good innings," Weaver said. "Unfortunately, we play nine."

Now, the Orioles are left to contemplate their recurrent follies.

* Where and when will they get a right-handed reliever? (Answer: after a postgame Weaver-Peters meeting, 250-pound sore-armed Tim Stoddard was recalled from AAA Rochester for immediate use and Storm Davis was farmed out.)

* When will a Baltimore outfielder next throw to a cutoff man in a vital situation? As Rick Dempsey said, "If Al hit either of two cutoff men, I'm sure the runner's out at the plate."

Weaver, trying to protect Bumbry, said the outfielder had told him he'd been trying to throw all the way home--an implausible, but permissible, notion. "I asked him where he was throwin' it--home or to the center of the infield, where it landed," said Weaver, pointedly. "He said, 'Home.' That's okay. But the center of the infield ain't so good. There's no bases there. They put all four of 'em at the corners."

* Finally, when is Weaver going to come out of his spring-long managing slump? His clubhouse is, uncharacteristically, buzzing with unavoidable second-guesses of moves such as calling for Stewart, not Tippy Martinez, tonight.

"When Sammy says he feels good, I feel good," Weaver said. "He said he felt good, but right now I don't feel so good."