Toronto Blue Jays pitcher Dave Stieb said it didn't take a psychologist to pinpoint what happened. "When a pitcher who relies on power doesn't have any pop in his fast ball and has trouble with the slider--the two biggest power pitches--that's what can happen."

What happened was that the Baltimore Orioles hit three home runs in the first three innings off Stieb, the American League's leading pitcher, and beat Toronto, 6-4, at Memorial Stadium tonight.

Stieb (8-4) came into game with more victories than any pitcher in the league and the best earned run average (1.66) of any starter. But tonight, he was gone after only 2 2/3 innings, taken out after John Lowenstein's two-run homer that gave Baltimore a commanding 5-1 lead. Eddie Murray and Al Bumbry had homered earlier for the Orioles.

Lowenstein, as usual, put the evening's performance into perspective. "The game of baseball, by its nature, is cyclical. We were fortunate to beat a man of his pitching capabilities."

Stieb had a different way of expressing what happened. "I just had a bad night, that's all," he said.

Mike Boddicker, who pitched five innings for the victory, said he felt fortunate Stieb's bad night came against the Orioles. "He'd been going so good," Boddicker said, "he was bound to have a bad game. I wasn't pitching that good myself. The breaking stuff kept me in, because the fast ball didn't have any pop or motion."

By the time Boddicker took the mound, Murray had given him a 2-0 lead with a Ruthian swat deep into the right field stands.

Stieb had retired the first two hitters, working in his usual hasty style by throwing every eight to 10 seconds. The usual style wasn't producing the usual results, however. Stieb walked Cal Ripken Jr., and started Murray with a ball outside.

Eight seconds later he threw a fast ball to Murray, who in one tremendously powerful swing hit it at least 450 feet. "That thing is out of any ball park in the world," said Boddicker.

The Blue Jays' Ernie Whitt ended an 0-for-13 road slump by hitting a home run in the second--his fourth of the year--that cut Baltimore's lead to 2-1. The Blue Jays lost a last chance to tie the game when Damaso Garcia (on a 3-2 pitch) was picked off first base seconds before Rance Mulliniks doubled down the third base line.

Bumbry countered with his home run, in the third, making it 3-1. It looked like Stieb would finish the inning without further trouble when he retired the next two batters. But Stieb, still not able to spot his slider, walked Murray. Lowenstein then hit his homer, also to right field, for the third run of the inning and a 5-1 lead.

Cliff Johnson, the Blue Jays designated hitter, hit his ninth home run of the season in the fourth but Bumbry drove in another run in the bottom of the inning to make it 6-2.

Then there were a few anxious moments for Boddicker. Mulliniks and Willie Upshaw opened the sixth with consecutive singles to left field. "I don't know if I was tired," Boddicker said. "But I wasn't hitting the corners as well."

Manager Joe Altobelli didn't want a struggling pitcher to face Johnson. So he brought in reliever Sammy Stewart, who obviously was aware that Johnson isn't one of the game's great breaking ball hitters.

Stewart threw a low fast ball and then a wicked slider and Johnson hacked furiously at strikes two and three.

Toronto did score one run, however, as Lloyd Moseby beat out a double play relay throw, allowing Mulliniks to come in from third. Stewart did allow one run in the eighth, on a double to left by Johnson and a single by Moseby. But he completed four innings for his second save of the season, as the Orioles won their sixth game of the last eight.

Baltimore remained percentage points behind Boston, which defeated Minnesota earlier this afternoon. Toronto, despite slipping into third place, one game behind, is still the surprise team of the league.

"They used to have four hitters to watch," said Stewart, "but now they've got nine."