The Baltimore Orioles today put left-handed pitcher Mike Flanagan on the 15-day disabled list and, as expected, recalled third baseman Tom O'Malley from Rochester. O'Malley may be in the lineup for Tuesday's 7:30 p.m. game against Seattle at Memorial Stadium.

Flanagan has tendinitis in his left elbow. He was put on the disabled list retroactive to Saturday so he will be eligible to be activated June 15. Doctors have told him not to pick up a ball for 10 to 12 days.

"We don't think it's serious," Orioles General Manager Hank Peters said, "but any time a pitcher's elbow or arm is concerned, you have to treat it like it's serious. We think it's best not to take any chances."

Even if Flanagan hadn't gone on the disabled list, the Orioles were determined to recall O'Malley.

Peters and Manager Earl Weaver talked on the flight home from California Sunday night and decided to make a change at third base, where the Orioles have been awful. Through 47 games, the team's third basemen have made 18 errors and batted in nine runs.

Floyd Rayford, the projected starter this season, hasn't had a hit in 28 trips and is batting .123. Juan Beniquez has hit but also has made eight errors in 12 games there, including five in his last four starts.

When spring training began, the Orioles expected O'Malley to fit in well, playing third when Rayford went behind the plate. Instead, O'Malley was so bad in the first two weeks of camp, both defensively and offensively, that he got only eight at-bats in exhibition games and was cut quickly.

Nonetheless, the Orioles have hope for him. He is among the leading hitters in the International League and entered tonight's game with a .305 average, four homers and 19 RBI. He has impressed scouts defensively, although he doesn't have great range.

"We've decided that maybe he's one of those guys who isn't a great spring training player," Peters said. "From all our reports, he has certainly been playing well."

He began his career with the San Francisco Giants' organization in 1979 and was in the major leagues in 1982 at age 21. He hit .275 in 92 games and in 1983 spent the entire season with the Giants, hitting .259 with five homers and 45 RBI.

But he started the 1984 season hitting .120 and was sent to Phoenix. He drifted to the Chicago White Sox and Detroit Tigers, then was traded to the Orioles for catcher Luis Rosado on May 23, 1985.

Weaver said he was uncertain whether he would start O'Malley on Tuesday against Seattle's Milt Wilcox, although he said O'Malley was going to get plenty of work in the next two weeks.

"I'm going to have to see how the stats stack up," Weaver said. "I'll decide when I get to the stadium."

The move again leaves the Orioles with nine pitchers, and Peters said, "Earl likes to use his bullpen, so you feel more comfortable with 10 pitchers. We'll see how this works out, and we're going to talk some more this week about some other moves."

The team apparently would like to send Rayford to Rochester to get back on track. But because he has three years' tenure in the major leagues, he can't be sent down unless he consents. So far, the club hasn't asked him, but he has indicated he's not keen on the idea.

That move will be discussed more Tuesday, and it's clear, with O'Malley up, the only action Rayford will see for a while is as a backup to catcher Rick Dempsey.

Orioles reliever Don Aase was named AL pitcher of the month for May. He was 1-0 with nine saves and a 0.69 ERA in 12 games.