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05/07/2013 7:50 PM ET

Berkman fine with pinch-hit role in NL parks

MILWAUKEE -- Lance Berkman is content to be used as a pinch-hitter during the Rangers' three games in National League parks this week. With no DH being used in NL parks, the only way Berkman can be in the lineup is if he plays first base. The Rangers aren't ready for that option, as Berkman is still recovering from two operations on his right knee last year.

Manager Ron Washington said it's a combination of Mitch Moreland hitting well and the club not wanting to take any risks with Berkman at this point in the season.

"We want to make sure this guy is ready to go," Washington said. "Right now, I know he's ready enough to be our DH. This guy is going to be big for us before the year is over. He's going to come up big, and when that happens, I don't want him on the disabled list because I put him at first base or the outfield."

Moreland went into Tuesday's game against the Brewers hitting .375 (21-for-56) with two home runs in his last 15 games. He was batting in the fifth spot in the lineup on Tuesday night for the first time this season.

"We have a first baseman," Berkman said. "It would be one thing if we didn't know who was playing over there. It's all about what gives you the best chance of winning, and he gives us as good of a chance as me. He's also playing good defensively at first base. It's all about risk vs. reward. Do you want to risk it just so I can get three or four at-bats?"

Berkman said his knee continues to get stronger, but not to the point where he can play multiple games in a row in the field.

"If Mitch got hurt in the first inning -- heaven forbid -- and they were looking for someone, I could do it," Berkman said. "If they want someone out there every day, I'm not ready to do it."

Prospects Buckel, Olt dealing with separate issues

MILWAUKEE -- Double-A Frisco pitcher Cody Buckel has been assigned to extended spring training, and Triple-A Round Rock infielder Mike Olt has been placed on the disabled list while waiting to see another eye specialist. The Rangers are still searching for answers to the problems plaguing two of their top Minor League prospects.

Olt, the No. 2 ranked prospect in the Rangers' system, has not played since April 25 after telling Rangers officials he was having problems with his vision. The club has sent him to two eye doctors without a definitive diagnosis. He is scheduled to see an advanced specialist in the next 10-14 days.

Olt was hitting .139 with one home run and six RBIs in 20 games before he came out of the lineup. He told the Rangers he had been dealing with the vision issues as far back as Spring Training.

"He said it has been bothering him, but he thought he could push through it as he saw more live pitching," general manager Jon Daniels said. "It finally got to a point where he reached out for help."

Buckel, the No. 4 ranked prospect, has been fighting persistent control problems and has walked 28 batters in 9 1/3 innings. The Rangers are sending him back to Surprise, Ariz.., where he can work with Keith Comstock, the organization's rehab pitching coordinator. Comstock is highly regarded for his ability to work with injured or troubled pitchers. Buckel is not injured. The Rangers believe his control problems are mental, and he could also see a sports psychologist at some point.

"We're going to use all our resources," Daniels said. "If you watched him throw for the first time, you wouldn't think he was scuffling, but it was just one bad outing. He's not missing by much, but he's missing consistently. We've got to get him back to where he should be. There is no timetable. He and Keith will let us know when he's ready. We want to give him time."

Perez slated for next Double-A rehab start

MILWAUKEE -- Left-hander Martin Perez, at Double-A Frisco on a medical rehabilitation assignment, will make his next start on Saturday against Corpus Christi. Perez, who allowed one run in four innings on Monday against Midland, is scheduled to pitch five innings.

The Rangers will evaluate him after that start. Perez could be close to being an option at the Major League level, but he will likely need two or three more outings. Perez was hit by a line drive in Spring Training and has been sidelined since March 4 with a broken left arm.

"It was an arm injury, but not a shoulder or elbow," general manager Jon Daniels said. "It's not so much a health deal, it's more about effectiveness and how sharp he is. The biggest thing is how he's doing and how the big league club is doing."

Daniels said it's not automatic that Perez would be added to the big league roster when he's at full strength. He could be optioned to the Minor Leagues and continue pitching there until there is a need at the Major League level. Daniels also said Perez could be an option for the bullpen if there is a need, but the preference is to keep him stretched out to provide depth for the starting rotation.

Right now, the Rangers are committed to rookie right-handers Nick Tepesch and Justin Grimm in their rotation. Tepesch is 0-2 with an 8.44 ERA in his last two starts, but he is still scheduled to pitch Sunday against the Astros. The Rangers have an off-day on Thursday, so they could push Tepesch back, but manager Ron Washington said they aren't going to do that.

"You have to allow these guys [to have] some bad outings and see how they go through it," Washington said. "There's no perfection in baseball. You're going to have adversity, so you want to see how they work through it. They don't need to be looking over their shoulder. They have enough concerns trying to get out Major League hitters."

Worth noting

• Catcher A.J. Pierzynski was scratched from Tuesday's lineup because of tightness in the oblique muscle in his right ribcage. Pierzynski has been out of the starting lineup in four of the last eight games while dealing with the injury.

• Colby Lewis, coming back from flexor tendon surgery, is scheduled to make his first rehab start on Thursday. He will pitch for Triple-A Round Rock against Las Vegas, and he is scheduled to pitch three innings. That will start the clock on a 30-day rehab assignment, so the Rangers will have to make a decision on Lewis within the first 10 days of June. He could be ready before that.

• Daniels said the Rangers aren't getting too caught up with what they'll have to do once Perez and Lewis are ready to come off the disabled list. Said Daniels, "If everybody is healthy and pitching well, we'll have a call to make. We're not there yet."

• Jeff Baker was not in the lineup on Tuesday with right-hander Wily Peralta pitching for the Brewers. Baker went into the game with a career .404 batting average (21-for-52) at Miller Park. That's the third highest among all players with a minimum of 50 at-bats there since the park opened in 2001.

• With all of the changes on the Round Rock pitching staff, the Rangers have moved Jacob Brigham back to the rotation. He has not allowed a run in eight relief appearances between Frisco and Round Rock this season, striking out 19 while allowing just five hits and seven walks in 14 2/3 innings.

T.R. Sullivan is a reporter for MLB.com. Read his blog, Postcards from Elysian Fields, and follow him on Twitter @Sullivan_Ranger. This story was not subject to the approval of Major League Baseball or its clubs.