CLEVELAND, JUNE 20 -- Thursday and Sunday promise to be big days for Baltimore Orioles right-hander Bob Milacki.

He will throw in the bullpen on Thursday to find out if his right shoulder is feeling well enough for him to take his regular turn in the rotation. If so, he will face the Red Sox at Fenway Park on Sunday -- and Manager Frank Robinson will find out if Milacki is pitching well enough to stay in the rotation.

The situation involves team doctor Charles Silberstein's diagnosis that Milacki has muscular weakness in his right shoulder, Milacki's insistence that he feels fine, and Robinson's opinion that if Milacki says he is not hurting, he should be pitching better than he has been. Then there is the general status of the Orioles' starting rotation.

Robinson said this evening if Milacki "is hurting I'm willing to give him the benefit of the doubt. But if he says he is all right and he's not doing the job, I have to make a decision based on that.

"Right now, I'm going to let him go out there next time. If he struggles again, that's when we have to see about making some kind of determination. I would consider removing him from the rotation."

But with starters Jeff Ballard and John Mitchell also unimpressive recently, Robinson asked, "How can I move three guys out of the rotation?"

Last season Milacki was 14-12 with a 3.74 ERA and 88 walks in 243 innings. This season he is 3-3 with a 5.02 ERA, 89 hits, 42 walks in 78 2/3 innings. In his last 10 starts, he has averaged less than five innings and compiled a 6.51 ERA.

Robinson and pitching coach Al Jackson asked Milacki if he was well enough to pitch Tuesday night. Milacki said yes and lasted 5 2/3 innings. He allowed three earned runs on seven hits and five walks, and Robinson had the bullpen working during each of Milacki's last four innings. The kicker, however, was a double to right-center and a homer to right by Jerry Browne, a switch hitter who began the game batting .223 and slugging .275.

"Guys are pulling the ball against him who shouldn't be," Robinson said. "That's maybe a tip-off something is wrong. Jerry Browne should not be hitting home runs off Bob Milacki to right field."

Milacki said "there could be a mechanical problem because of the stiffness" in the shoulder, but he also said "I've hurt my arm once before and I know what it's like when I can't throw. I know the difference. I think this is something I can throw through." Nixon Recalled

The Orioles recalled outfielder Donell Nixon from Class AAA Rochester to replace Phil Bradley, who will have surgery Friday to repair torn cartilage in his wrist. Nixon hit .255 in 30 games at Rochester. . . . Relief pitcher Mark Williamson, who left Tuesday night's game because of a stiff back, said he could pitch a bit tonight. . . . Pitcher Dave Johnson returned to Baltimore this evening because his wife apparently was going into labor. He is scheduled to pitch Saturday in Boston. McDonald Sharp

Ben McDonald allowed four hits and one run in six innings tonight to get credit for the Red Wings' 3-1 victory over the Richmond Braves in Rochester, N.Y. He is 3-2 with the minor league team.

Mickey Weston retired two batters for his fifth save. Sam Horn's pinch-hit, two-run single highlighted a three-run sixth inning as the Red Wings completed a sweep of their International League doubleheader.

The Red Wings won the first game, 8-2, on Eric Bell's six-hitter. He's 7-4. David Segui drove in four runs and Tony Chance and Leo Gomez had two hits each for Rochester in the opener.