If a team's own opinion of its ability plays any part in its ability to win, then the Baltimore Orioles are going to be tough Birds this season.

The O's think they can pin the ears back on any team they play-just as they did again tonight, blasting Oakland, 8-2, with three consecutive home runs.

"I've figured it out," Manager Earl Weaver said after his Orioles moved back into first place with their 16th win in 18 games. "My players don't trust me. They won't let me make any decisions.

"By the time it gets to my part of the game-the late innings-we're so far ahead that I got nothin' to do."

This evening the Birds fell beind, 2-0, then raged back with frightening self-assurance, the barrage culminating in the sixth inning when Eddie Murray, Lee May and Gary Roenicke hit back-to-back-to-back homers for the final four runs. All three drives were crushed.

"Our hitting is for real," said a beaming Mike Flanagan, who pitched an almost disdainfully easy six-hitter, fanning six and in one stretch getting 21 outs on the last 21 batters he faced, thanks to two double plays.

"In the past, we (the pitchers) had to win 2-1 or 3-2. If we fell behind, like we did tonight, you might worry. Now you just sit back and wait for it to happen. We look like those old Oriole power clubs that I only heard about . . . with Brooks and Boog and Frank.

"We just come out night after night and do an awesome number on people's heads."

Over its last 18 games, Baltimore has outscored its victims, 116-48. The O's began tonight with six regulars hitting over .300.

Of all the scalding Oriole bats, Eddie Murray's is most prominent at present. Murray stretched his hitting streak to 19 games with a double and the homer.

If baseball has a most hidden star, it is probably Murray, who was second in the American League in total bases last year.

"There's no telling what he will do," said Singleton. "Start with 300 career homers, then start adding by the hundreds-who knows where he'll stop. He's only 23."

"He's enormously unkown," said Coach Frank Robinson, creating an interesting phrase. "Fans say, 'who's Eddie Murray?' Players just say, 'Man give me that guy's future.'"

In his 19-game tear, Murray has hit .411, with 22 runs batted in, raising his average to .333 from .171.

"It's nice to hear cheers, but I can get along without them," said Murray, who assiduously avoids the spotlight, playing a game that epitomizes energy conservation.

"What interests me is doing well in the crucial moments that win games. I just say, 'Why depend on anybody else in the clutch. I'm here.'"

Murray ignited the O's tonight. With two out in the third, his team behind, 2-0, he smacked a double to left that started a two-run rally. May singled him home, took second on a passed ball, then scored on Roenicke's single. That trio would haunt the A's again.

Next inning, the O's were back, betting on the door as Rick Dempsey, Al Bumbry (who is on a 12-game streak) and Singleton all hit opposite-field doubles off the corner walls for two runs and a 4-2 lead.

That was mere preliminary to the fireworks in store. With two out in the sixth, reliever Jim Todd thought his worst enemy was the home plate umpire, who kept asking to inspect balls to make sure Todd wasn't tossing spitters.

Todd got so furious that he rolled the ball to the plate for one inspection.

He should have rolled it up to Murray, May and Roenicke.

After Singleton, whose slugging percentage has been above .900 the last 18 games, had singled, Murray hit a patented frozen rope, a screamer into the right-field bleachers.

"I've only got three homers this year because I'm too strong," Murray explained in typical laconic fashion."I'm getting too much top hand in my swing and I'm hitting some awful hard singles. If I was weaker, I'd get under it (the ball) more."

If Murray's homer raised the question, will it get there, then May's made the crowd of 7,126 wonder, will it ever come down.

It finally did, in the left-field runway about 420 feet away.

Todd, a gentlemen even in distress, showed his class by not knocking down Roenicke-who needed 30 stitches after a beaning last month.

"I admired that," said Roenicke.

Roenicke also admired the scorching homer he hooked around the left-field foul pole on the first pitch.

Those looking for symbolism might note that the last Orioles to hit three homers in a row were named Robinson, Powell and Robinson in that World Series year of '69. CAPTION: Picture 1, Eddie Murray; Picture 2, Mike Flanagan