Around the American League, Scott McGregor is regarded as a junk pitcher, a baffling half-speed magician who gets batters out by treachery and guile.

Tonight, McGregor and the Orioles dispatched the Minnesota Twins, 6-0, in 2 hours 1 minute and it was McGregor's little-respected fast ball that did the job.

"Eighty-one fast balls out of 110 pitches thrown," said pitching coach Ray Miller in describing McGregor's fifth complete game and fifth victory of the year against three losses. Miller then took issue with the prevailing view of his ace left-hander's stuff.

"Mauch (California Manager Gene) says, 'How can he (McGregor) get away with that junk?' " mused Miller.

But 81 fast balls up to 84 mph do not constitute junk, said the coach. "With his changeup," said Miller, "the hitters lay back and wait for the off-speed stuff. Then when he throws the fast ball, all they can do is pop it up."

And McGregor said the fast ball tonight was as good as he can remember. "I could hear it pop in the catcher's mitt," he said. For McGregor, that's rare.

The Orioles scored three quick runs in the second inning and three in the fourth off Twins starter Pete Redfern, who went all the way in defeat. Then Baltimore turned the show over to McGregor, who struck out six, walked none and gave up but five hits, all singles.

"He's a family man," said Manager Earl Weaver. "He went out there and got us all home an hour and a half early to see our wives and kids by pitching a good ball game."

It was left-hander night before 12,598 fans at muggy Memorial Stadium.

Weaver started six left-handed batters in addition to his left-handed pitcher. The strategy was to pound right-hander Redfern early and often, and it worked.

Three left-handed hitters getting rare starts tonight got on base a total of six times and scored five of the Baltimore runs.

Jim Dwyer, in right, walked and scored twice. Catcher Joe Nolan and first baseman Terry Crowley each singled and doubled, Nolan scoring twice and Crowley once.

But the game-winning RBI went to designated hitter Ken Singleton, with an assist to Twins center fielder Tom Brunansky.

Singleton led off the second inning with a drive deep to left center and Brunansky took off in hot pursuit. The 6-foot-4 outfielder caught up with the ball just before it cleared the wall 380 feet from the plate. He leaped and grabbed it in his glove, but when he came down his arm struck the top of the wall, jarring the ball loose and over the top for a 1-0 Orioles lead.

Baltimore scored twice more, on Cal Ripken Jr.'s RBI double and Lenn Sakata's sacrifice fly, then put the game away two innings later when Nolan doubled a run home and Ripken brought home two with a blooper over a drawn-in infield.

McGregor didn't allow a runner past first base until the ninth inning, when Ron Washington and Larry Milbourne singled back to back. Weaver came to the mound for a visit and said he told his pitcher to slow the pace to give a reliever time to warm up.

But it was unnecessary. A grounder, fly ball and a popup ended the threat and gave the Orioles the deciding game in this three-game series.

Ripken's two hits tonight continued his progress. After a dreadful start, he is batting better than .400 in his last 10 games (15 for 37) and had raised his average from .165 to .230 by the start of tonight's game.

Ripken said that during his slump he was hitting so badly he couldn't even get hits off his father, third base coach Cal Sr., in batting practice. In game situations, "I was lost out there," he said. "I didn't know any of the pitchers. But after you see them a couple of times, you get a good idea how they want to pitch you, and then you can make them adjust."

Ripken also said the mood of the Orioles has changed dramatically. On the West Coast swing, which ended at 6-5, "We could have been 9-2 with a couple of breaks. Everybody's relaxed," said Ripken. "They know we're going to win."

The Orioles leave Friday morning for a three-game series in Toronto.