MINNEAPOLIS, JULY 1 -- Baltimore Orioles pitcher Jeff Ballard, who has struggled throughout this season, will be out of the starting rotation until at least the all-star break, Manager Frank Robinson said today.

Robinson said the club, which played the Minnesota Twins tonight at the Metrodome, will use a four-man rotation for the six games it has until the break.

Ballard's move to the bullpen is a result of the left-hander's 1-9 record and 5.28 earned run average, the state of Baltimore's bullpen and the schedule.

Since the Orioles do not play Monday, John Mitchell will get an extra day of rest before facing the Rangers on Tuesday night in Texas, and Dave Johnson, Bob Milacki and Pete Harnisch will have their normal four days' rest before pitching again.

Because Ballard's regular turn would have been Wednesday, Mitchell and Johnson likely will start Saturday and Sunday in Chicago on three days' rest. But those games are followed by the all-star break, which is only two days this season because of the spring training lockout. The All-Star Game is July 10 in Chicago.

The bullpen has been down to one left-hander (Kevin Hickey) since Friday, when Joe Price went on the 15-day disabled list with a strained back.

Moving Ballard "gives me a little more maneuverability," Robinson said. "And maybe he can get himself back on track down there. Even if he only warms up, he could get something out of it."

Ballard seemed to take the move well, even though Robinson said the rotation after the all-star break could be set up so that Ballard might have two weeks between starts. His last start was Thursday in Baltimore against the Indians.

Robinson "told me it's not a demotion," Ballard said. "Sure, I'd rather start on Wednesday, but it's better for the team in the long run. It doesn't surprise me. In April, when you have off days, you sometimes go with four. And right now I'm the fifth starter."

Ballard has not won since May 27 in Texas. He has one win in 17 starts since Sept. 24. He is among the major league leaders with 16 home runs allowed in 87 innings. He allowed 16 homers in 215 1/3 all of last season, when he went 18-8 with a 3.43 ERA. Down on the Farm

Pitcher Ben McDonald's experiment with throwing American League baseballs was deemed a provisional success by Class AAA Rochester Manager Greg Biagini.

McDonald has been having problems with blisters on his right middle finger that were caused by the seams of the Wilson-manufactured International League baseball, which apparently are higher than those of the Rawlings-manufactured AL ball.

So, while the Red Wings played Saturday night in Buffalo, McDonald threw 90 pitches in five innings of a simulated game in the bullpen, using some of the dozen AL balls Orioles General Manager Roland Hemond shipped to the Red Wings. McDonald experienced no discomfort, reported Biagini, who said "there is definitely a difference in the balls."

McDonald "threw his fastball, curveball and change-up, and he looked great," Biagini said from Nashville, where the Red Wings played tonight. "But he didn't throw as hard as he would in a game."

McDonald was scheduled to start Saturday. The Red Wings use a five-man rotation and they have no off days until the July 10 all-star break, but Biagini said he didn't know when McDonald would start again.