Earl Weaver had an idea tonight, perhaps the only good Baltimore notion in his Orioles' two-hit, 6-0 loss to the Seattle Mariners and their All-Star left-hander, Floyd Bannister.

The 51-year-old manager decided to take the ball and glove away from Dennis Martinez on the mound of Memorial Stadium and do the pitching himself.

Weaver took his stretch at chest level, ball securely in the black glove, then quickly stepped off the rubber before starting his pickoff move to first base.

The crowd of 13,529 roared its approval. Maybe the fans liked the fierce way Weaver glanced over his shoulder at first to hold the runner. Maybe they liked how natural he looked with a glove and ball in his little hands as he stood tall on the mound, comfortable as the two-time bush league MVP he was.

That's where the good idea ended.

Unfortunately, Weaver never threw a pitch. He was just making a pantomime protest, demonstrating to second base umpire Terry Cooney, who had just ejected him for general impertinence, what was and what was not a balk.

"They (umpires) don't speak English, so you have to act things out for 'em," growled the hoarse Weaver after his second ejection in six days and No. 83 of his career. "When you deal with stupidity, you have to act stupid."

Weaver's tirade, ejection and subsequent demonstration was, by a wide margin, the highlight of a particularly flat performance by the Orioles.

"It's hard to look good when you're walkin' around with the bats stuck in your ear," grumped Weaver, his Orioles now 4 1/2 games behind Boston and 5 behind Milwaukee. "Bannister was great."

The Orioles showed in many ways this muggy evening just how difficult their pursuit of the Brewers and Red Sox figures to be.

As has been the case all year, Baltimore showed an uncharacteristic, yet undeniable weakness. Martinez, now 9-7 with a lackluster 3.97 ERA, was knocked out in the third after allowing seven hits that led to four runs.

In particular, Martinez needed the sort of snazzy pickoff move that Weaver demonstrated. After five seasons of remedial major league work, Martinez still has one of the worst moves in the American League and is a constant victim. This night, he balked, allowed two clean steals and was the victim of a hit-and-run on another steal.

"Dennis has had the same move for five years. He steps off the rubber, then throws to first," said Ray Miller, the Orioles' pitching coach. "Hell, that's why he never picks off anybody and everybody steals on him. The runners just watch his back foot. We keep trying to get him a better move. Every player in the American League knows Dennis takes his (right) foot off the rubber, but, now, two umpires within a week don't know it. They must not be doing much homework."

After allowing a home run to Richie Zisk in the second, Martinez was undone in the third by his own bad move and the Mariners' slap-hitting. Julio Cruz singled and stole second by an eyelash despite a near-perfect throw by Rick Dempsey. With one out, painfully slow Bruce Bochte hit an RBI double to left. Then, to the Orioles' amazement, he chugged to third with a steal as Martinez fell asleep, Dempsey threw into the dirt and Dauer forgot to cover in time.

After a walk to Al Cowens, Zisk executed an excellent RBI hit-and-run grounder to right to knock out Martinez. Reliever Ross Grimsley finished the damage, allowing an RBI single to Dave Henderson, only the fourth "inherited" runner in 20 that he has allowed to score this year as a reliever.

Later, Grimsley yielded three singles and a run in the fourth and a homer by Henderson in the seventh.

Martinez's mediocrity this year just makes him part of a club. Mike Flanagan (6-8), Jim Palmer (4.15 ERA), Sammy Stewart (4.40) and, to a slight degree, even 11-6 Scott McGregor (3.87 ERA) are all parts of a guilty rotation that has contributed to a 3.99 team ERA. The bullpen of Tim Stoddard (3.57) and Tippy Martinez (3.80) already has been pilloried enough for its so-so season.

Over the years, Palmer has greeted Weaver's arrival on the mound more than once with a flippant, "Why don't you pitch?" Weaver may soon be tempted.

As this loss to the 46-42 Mariners showed, the Orioles of '82 are an inconsistent, herky-jerky team. On one hand, they entered the game with the best record in baseball since May 2: 34-20. On the other hand, their season record, which is what counts, is 45-39.

The offense has been their salvation. The team's statistics project to 782 runs and 181 homers for the year; the club records are 805 runs and 182 homers.

Against the hard-throwing Bannister, 27, the Orioles had few chances and did nothing with them. Gary Roenicke doubled over the third base bag in the second and Lenn Sakata singled to left in the seventh.

In '80, Bannister had a three-hitter and four-hitter against the Orioles. In studying his precious statistics, Weaver could find only two players on his team with career averages over .167 against Bannister.

Nevertheless, in both the second and sixth, the Orioles loaded the bases with two outs. Twice, the next hitter swung at the first pitch. The first, Rich Dauer popped up. The second, Ken Singleton, did something even worse--he absolutely crushed the ball toward the left field wall.

The crowd rose to cheer a grand-slam, game-changing homer. Instead, Singleton, batting only .182 right-handed for the season with just two doubles and no homers, watched as his best bolt died before it even got to the warning track.

The Orioles, like that drive, seem in serious need of some extra jolt of juice before they can reach their goal.