Brian Downing drove in a pair of runs and starting pitcher Dave Frost hurled a strong 72/3 innings yesterday to lead the California Angels to a 4-2 victory over the Baltimore Orioles at Memorial Stadium.

The loss, the second to the Angels in as many days, dropped the Orioles to fourth place in the American League East, one-half game behind New York and 71/2 behind first-place Boston. The Angels stayed within four games of West Division leader Kansas City.

The Orioles failed to give the crowd of 15,350 much to cheer about in the early innings, picking up just three hits in the first five frames off sidearmer Frost, who was facing the Birds for the first time. No Orioles reached second base through the initial five innings.

In fact, the first Baltimore toe to touch home plate was that of Manager Earl Weaver. Weaver came out and kicked dirt over the plate in the eighth inning after being thumbed for throwing his hat to the dugout floor.

Weaver, later asked the reason for dirtying his cap, explained cloudly, "Paul Hartzell (Angel starter) did it Saturday night. He even threw it onto the field. I figured it was the thing to do. I thought I could at least do that in the dugout." Weaver, ejected from his fifth contest of the season, plans to protest the game.

The Angels picked up a run in the second after designated hitter Don Baylor walked to lead off. Joe Rudi singled him to second, and Downing's single to center drove in Baylor.

The Orioles threatened to score in the sixth when Eddie Murray got on with a one-out single. Ken Singleton moved Murray to third with a double. But the duo was stranded after Doug DeCinces fanned and Pat Kelly popped to short.

California picked up two more in the eighth.Flanagan sandwitched walks to Merv Rettenmund and Ron Jackson around the inning's first out. After a foul out and a wild pitch, Rudi and Drowning smacked consecutive run-scoring singles to make it 3-0. That activity chased Flanagan, setting him up for his ninth loss against 13 victories.

With Rich Dauer on base in the Oriole eighth on a fielder's choice, Murray socked his third hit of the game, sending Dauer to third. Singleton then bounced to second to score Dauer. DeCinces slugged a double to left to score Murray and make it 3-2. The RBI was the 30th of this month for DeCinces.

The Angels picked up an insurance run in the ninth when pich-hitter Lyman Bostock singled in Miller, who himself had singled to open the inning.

Dave LaRoche, who had relieved Frost in the eighth, struck out Rick Dempsey, got Mark Belanger to fly out, and fanned pinch-hitter Carlos Lopez to strand leadoff hitter Lee May on first. May had singled.

The save was LaRoche's 15th, tying him with New York's Rich Gossage for the league lead.