Before tonight's games began, all circumstances seemed right for Baltimore to move past Boston and into first place in the American League East. Not only were the Orioles playing Seattle, in last place in the West, but Jim Beattie, a pitcher they had handled easily two weeks ago.

But Beattie pitched well for 6 2/3 innings tonight, and Seattle scored four runs off Scott McGregor in the first two innings. The Mariners, with Al Cowens getting three of the five bases they stole, used that early lead to take a 6-4 victory before 9,605 in chilly Memorial Stadium.

As a result, the Orioles are 1 1/2 games behind Boston, which defeated the West-leading California Angels and Tommy John, 8-2, in Fenway Park.

Beattie raised his record to 2-1, with late help from three relievers, including Bill Caudill, who earned his sixth save by striking three of the six batters he faced.

McGregor, on the other hand, was gone after the third inning. "He wasn't pitching his game," said Baltimore Manager Joe Altobelli. "He just didn't have it tonight."

After winning his first three decisions, McGregor has lost his last two, giving up nine earned runs in seven innings.

McGregor's replacement tonight, Don Welchel, allowed only one hit over four innings. "The kid did a hell of a job," said Altobelli.

Problem was, Baltimore was already behind, 4-0, and the Orioles weren't hitting.

Jamie Allen, Seattle's stocky third baseman, homered 430 feet to center field for Seattle's first run. Cowens followed with a double and was joined on the bases by Dave Henderson, who walked. On McGregor's first pitch to Todd Cruz, Cowens and Henderson executed a double steal so smoothly that catcher Joe Nolan didn't even throw.

The steal resulted in a run, as Cowens scored on a ground out by Cruz, for a 2-0 lead. McGregor walked Jim Maler to start the second inning and allowed a double to Julio Cruz to again put runners in scoring position. This time, McGregor wasn't fortunate enough to get a ground out.

Allen, who had hit home runs in his last two times at bat--homering against Boston on Sunday--came to the plate again, looking at the center field fence. "I was thinking how great it would be to hit three in a row," he said. "But I don't consider myself a home run hitter. I told myself, 'You're a line drive hitter. Look for something you can drive.' And it worked out."

It worked out that McGregor threw an 0-2 pitch belt high over the middle of the plate. And Allen, the line drive hitter, lined a drive into left-center for a double that scored both runners for the 4-0 lead.

It went to 5-0 in the fifth, even though the Mariners did not get a hit. Cowens reached base on a grounder to first when umpire Drew Coble ruled that Welchel didn't touch the base after taking a toss from Eddie Murray.

That sent Altobelli into a rage. Before he could sit down, Cowens stole second on a very close play, bringing Altobelli out for another argument. Cowens stole third about 30 seconds later, again drawing no throw from Nolan. Henderson's sacrifice fly scored Cowens.

"We've been struggling, so I just decided I'd take off tonight," said Cowens. "We need to create some excitement. We need to keep doing this to win."

As Altobelli pointed out, the run didn't seem important at the time, but it did in the seventh, when Baltimore got a leadoff single from Rich Dauer and, after two were out, a double from Al Bumbry and a walk from Dan Ford. Cal Ripken hit a two-run double and the Orioles scored a third run when reliever Bryan Clark threw a wild pitch. Those three runs, added to Nolan's home run in the fifth, pulled Baltimore within 5-4.

But the decision Seattle Manager Rene Lachemann made to pull Beattie for a left-hander paid off. Murray, hitting .194 from the right side (.373 from left), flied weakly to right, ending the rally.

"I want Murray and (Ken) Singleton to see a left-hander and hit right-handed," Lachemann explained afterward. "They're both hitting under .200 from the right side."

Seattle got its final run in the eighth when Sammy Stewart walked two men and gave up a single to Maler.

Nolan, summarizing his team's evening, said, "We just played bad."