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6/18/2013 7:44 P.M. ET

Despite dominant stretch, Perez staying in Minors

ARLINGTON -- Left-hander Martin Perez threw six scoreless innings for Triple-A Round Rock in a 12-2 victory over Oklahoma City on Monday night and is 4-0 with a 1.13 ERA in his last four starts. But the Rangers are not ready to bring him to the Major Leagues.

"The only conversation we had was he threw the ball well again [Monday] night," manager Ron Washington said. "End of conversation."

The Rangers are staying with Justin Grimm and Nick Tepesch in their rotation for now. Grimm, who is 0-2 with an 11.40 ERA in his last three starts, will pitch again on Wednesday against Oakland. Tepesch allowed six runs in 3 2/3 innings against the Athletics on Monday and is 0-3 with a 5.79 ERA in his last six starts, but he is still scheduled to pitch on Saturday against the Cardinals.

"They just need to start getting more outs deeper in the ballgame," Washington said. "That's what we want them all to do, start executing better."

Tepesch retired nine of the first 10 batters he faced on Monday night before giving up six runs the fourth inning.

"It's about making pitches ... not putting a pitch where you need it to be," Tepesch said. "I have ups and downs during the season, it's all about how fast you can make adjustments. It's all about making pitches."

Rangers place Baker on DL with thumb sprain

ARLINGTON -- Jeff Baker is still unable to throw a baseball or grip a bat, so the Rangers placed him on the disabled list on Tuesday with a sprained right thumb. The Rangers also optioned first baseman Chris McGuiness to Triple-A Round Rock while calling up catcher Robinson Chirinos and left-handed pitcher Joseph Ortiz.

Baker has not played since last Wednesday, a day before injuring the thumb in a pregame over-exuberant high-five with an unidentified teammate. He has not been able to resume baseball activities. The Rangers were hoping Baker would be ready by this weekend, when they play the Cardinals in St. Louis. But that's not going to be the case.

"It's progressing, but I'm progressing in baby steps," Baker said. "The decision was made, now I need to get ready. It's frustrating, but it's out of my control. The biggest thing is to get healthy and don't have any setbacks."

McGuiness was sent back to Round Rock after going 6-for-34 with one RBI and 13 strikeouts in 10 games since being recalled on June 6. The Rangers are expecting Mitch Moreland to come off the disabled list on Friday and will likely use Lance Berkman or Chirinos at first base in the next three days. Berkman started there on Tuesday night vs. the A's. The Rangers may start Chirinos on Wednesday with left-hander Tommy Milone pitching for Oakland.

"If Berkman comes off the field tonight feeling good, you might see him out there [Wednesday]," manager Ron Washington said.

Chirinos is primarily a catcher, but he can play first or third base if needed. He gives the Rangers the versatility they are losing with Baker sidelined. But the Rangers especially miss Baker when facing left-handed pitching. He is 17-for-44 (.386) with eight home runs off left-handers this year.

The Rangers called up Ortiz to give them an extra left-hander in the bullpen after Neal Cotts pitched 2 1/3 innings on Monday night. Robbie Ross has also been carrying a heavy load and the Athletics had five left-handed hitters in Tuesday's starting lineup.

"We just felt we needed to get another left-hander up here," Washington said.

Berkman back in lineup after two-game hiatus

ARLINGTON -- Lance Berkman was back in the lineup on Tuesday after getting two days off. But he was batting fifth in the order after batting exclusively in the third spot. A.J. Pierzynski, who was hitting .382 in his last 19 games going into Tuesday, was moved up to the No. 3 spot. Berkman was hitting .192 in his last 19 games.

"I just decided to give Berkman less stress, so I moved Pierzynski to No. 3," manager Ron Washington said.

Berkman started at first base, as Washington used Nelson Cruz at designated hitter for only the second time this season. Craig Gentry started in center field with a right-hander on the mound and Leonys Martin was in right field.

Gentry went into the game with four hits in his last 33 at-bats, dropping his season average to .219. That's not what the Rangers were expecting after he was one of their more impressive players in Spring Training. Gentry earned a spot on the roster by hitting .351 with a .614 slugging percentage in Arizona, but he has struggled in his center-field platoon arrangement with Martin.

"Coming out of Spring Training, I felt great," Gentry said. "I'm just not having the success I thought I could have here. Not getting real consistent at-bats. It's tough to come out of it, but that's my job. I've got to overcome it."

Texas taking it slow with Ogando's rehab

ARLINGTON -- Pitcher Alexi Ogando, on the disabled list with inflammation in his right shoulder, is still not 100 percent. Ogando said he is still experiencing some inflammation in the shoulder, and that's why he has not started throwing off a mound again. Ogando, on the disabled list for the second time this season, hasn't pitched since June 5 in Boston.

"I'm feeling a lot better," Ogando said. "I haven't felt any pain, but I'm still feeling a little inflammation."

Ogando, who returned to the rotation this season after being used as a reliever last season, was also sidelined from May 16-June 4 with triceps tendinitis. The Rangers still want to use him as a starter, but they are taking it slower this time to make sure Ogando is fully recovered.

"That's what I want. ... I want to continue to be a starter," Ogando said. "That's why I want to make sure my arm is 100 percent this time."

Worth noting

• Joakim Soria was cleared to begin a medical rehabilitation assignment with Double-A Frisco on Thursday. It will be the first time he's pitched in a game since undergoing Tommy John elbow reconstruction surgery on April 3, 2012.

• Matt Harrison (back surgery) continues to play catch on flat ground, and Colby Lewis (flexor tendon surgery) has been cleared for a second bullpen session off the mound on Thursday.

• Nelson Cruz was hitting .203 against the Athletics over the past five seasons before delivering two home runs, a double and four RBIs on Monday night.

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.