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8/6/2013 9:45 P.M. ET

Harrison becomes first line of defense

ANAHEIM -- Left-hander Matt Harrison received a promotion on Tuesday. He is now next in line for succession to the Rangers rotation in case of injury now that Colby Lewis is sidelined for the rest of the season because of his impending hip surgery.

The only problem is Harrison isn't ready. He threw a bullpen session on Tuesday at Angel Stadium and will start for Triple-A Round Rock on Friday. He is hoping to throw 65 pitches in his third outing on medical-rehabilitation assignment.

"It's definitely unfortunate what's happened with Colby," Harrison said. "He was trying to pitch through a lot. I have a lot of thoughts and prayers for him and his family that he can get back as quickly as possible. I'm just taking it day to day. Everything is progressing well. I'm just getting ready for my next start. Hopefully if they need me I'll be ready."

The Rangers don't need him right now. Yu Darvish, Derek Holland and Matt Garza are locked into the rotation, and Martin Perez is coming off two strong starts against the Angels. Alexi Ogando is the one bringing up the rear. He has made three starts since being activated off the disabled and is 0-1 with a 4.61 ERA. He has yet to make it through more than five innings.

"Of course he needs to pick it up," manager Ron Washington said. "But he's not hurting, so since he's not hurting, I'm not concerned. He'll figure it out. Right now it's his command. He may go out tomorrow and find it. We know he can get outs. We haven't had any discussions on him. We just want him to get better."

Harrison will likely need two or three more starts before he is an option for the rotation. He has been sidelined since April after undergoing two surgeries to fix a herniated disk in his lower back.

Daniels: PED issue complicates player evaluation

ANAHEIM -- One of the real challenges for Major League executives in acquiring talent is evaluating the possible use of performance-enhancing drugs by players of interest. Rangers general manager Jon Daniels said that is a struggle for everybody.

"That's one of the real challenges in player evaluation," Daniels said. "How do you know ... your own players, in the Draft and Latin America or free agents or trades? I don't think we can truly know. There is so much money involved, the science behind it and the testing, the avoidance of testing -- obviously not just baseball, but all sports. That's a very challenging piece for us to make player evaluations. The reality is some of us really don't know."

The Rangers lost Nelson Cruz on Monday when he accepted a 50-game suspension from Major League Baseball for violation of the Basic Agreement and the Joint Drug Prevention and Treatment program. Cruz is a free agent after the season, and Daniels said the Rangers have left "open" the possibility of re-signing him, but that's a decision that will be made later.

But there is also a question of how this will impact Cruz, who otherwise might have been able to command a significant multiyear contract as one of the premier free-agent power hitters on the market.

"It's hard to say," Daniels said. "I give it a lot of thought. You wonder how you would handle it if you were in that position. I don't think there's an easy answer. It's like with any free agent. Beauty is in the eye of the beholder and how each club values players. Melky Cabrera got a two-year deal last year.

"I don't think you can really predict it. It's all a function of individual club situations and circumstances and how a player handles it and how that player is perceived by his peers, etc. Nellie made the best decision he could for himself given the situation. It's really hard to speculate on how it would have turned out."

Murphy returns to left field

ANAHEIM -- David Murphy was back in left field for the Rangers on Tuesday, one game after having a rough night in right field. Murphy, replacing Nelson Cruz in right, misplayed two fly balls, and manager Ron Washington decided he was better off in left. Engel Beltre, who started in left field on Monday, was in right field on Tuesday.

"I'm just trying to get everybody comfortable," Washington said. "David has played right field before, and he's comfortable out there, but he's more comfortable in left field. I trust David no matter where I put him."

Beltre played mostly center field in the Minor Leagues but has played both corner spots. Leonys Martin is the Rangers' regular center fielder, but Washington likes to shift him to a corner when Craig Gentry is in the lineup. Washington said Gentry is his best defensive center fielder.

Washington said that when Martin does play on the corner, it will most likely be in right field. Martin has played six games in left and 16 in right, and Washington believes he is better in right.

"He's better at seeing the ball from center toward right," Washington said. "He's not as comfortable in left and I don't want him out there scared. I want him playing with aggressiveness."

The Rangers want to look at Joey Butler in left field. He played mainly right field in the Minor Leagues because he has an excellent throwing arm. But he could be an alternative in left for Murphy against left-handers.

A's Melvin says Rangers will be fine

ANAHEIM -- The Rangers will be without outfielder Nelson Cruz for the rest of the regular season, and that may seem to benefit the Athletics, who entered Tuesday with a two-game lead in the American League West. But A's manager Bob Melvin said he didn't see it as all that beneficial to his team.

"They have a good lineup as it is," Melvin said. "They've bolstered their pitching staff, which makes them tough. Not only do they have a strong rotation, they have a deep bullpen. I don't think taking one hitter out of their lineup, albeit one that's produced a lot for them, really changes our feelings about them, nor should it."

Angels manager Mike Scioscia said the issue isn't how it impacts the Rangers on the field.

"I don't think that's neither here nor there," Scioscia said. "The broader picture is just from a standpoint of what baseball is about. This needs to be cleaned up and taken care of. The fact of what happens in a division, happens on a team -- there are a lot of players that maybe miss an opportunity because someone above them is playing at a level they shouldn't because of PEDs. That's as damaging as anything that's going to happen in baseball."

Worth noting

• Lance Berkman, who has been on the disabled list since July 7 with left hip inflammation, had a good day of batting practice on Tuesday, and the Rangers are hoping he'll be ready for a rehabilitation assignment this weekend. Said manager Ron Washington, "It looks like he's getting through the ball better. We'll see how he feels after we finish here. We'll definitely go on how he feels."

• Nick Tepesch, who has been sidelined since July 6 with inflammation in his right elbow, is still limited to long toss on flat ground.

• Alex Gonzalez, who was the Rangers' No. 1 pick in the 2013 First-Year Player Draft, was promoted from Class A Spokane to Myrtle Beach. He was 0-4 with a 4.56 ERA in nine starts at Spokane. But in his last three starts, he allowed one run on seven hits and two walks while striking out nine.

• Two pitchers were promoted from Myrtle Beach to Double-A Frisco: Jerard Eickhoff (7-3, 3.41) and Nick Martinez (10-7, 2.87). Mike Zouzalik was promoted from Class A Spokane to Myrtle Beach. He had a 1.35 ERA and four saves in 14 appearances.

• Lewis Brinson, the Rangers top pick in the 2012 First-Year Player Draft, has been activated off the disabled list at Class A Hickory.

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.