ARLINGTON, Texas -- Rangers third base coach Gary Pettis spent several minutes during Wednesday's batting practice working with Leonys Martin and Jurickson Profar on their approach to stealing second base.

In fact, it was Martin who went to Pettis to ask for extra work after he'd been caught stealing two days in a row and in three of the last four games.

Martin said he's been a little anxious on the basepaths, though manager Ron Washington said he hasn't seen it that way. Martin has been thrown out on six of his last 15 stolen-base attempts after swiping 16 in a row.

"He's been thrown out," Washington said. "I haven't seen anything about him being overanxious."

To their credit, Astros catcher Carlos Corporan and Brewers catcher Jonathan Lucroy both made perfect throws to nail Martin at second base in the last two games.

Still, if Martin gets himself in the right place with his lead and his jump, even the best catchers -- except for St. Louis' Yadier Molina -- can't throw him out. That's the Rangers' thinking.

"We just want to make sure his first movement is to second base," Pettis said.

Martin has been studying his baserunning on video. That prompted him to go to Pettis, who by the way, had already planned to go to Martin for a refresher course.

"I just need a better jump," Martin said. "I have to make a few adjustments on my try to steal second base."

Berkman's rehab: The Rangers don't appear to be in a hurry to bring designated hitter Lance Berkman back Friday when they open a three-game series against the Seattle Mariners.

Berkman was slated to play his fourth rehab game on Wednesday night, the second one for Double-A Frisco. That has been plenty of games and at-bats for Rangers' hitters on rehab assignments, but Berkman's ability to run the bases is still a concern.

"We'll see how he feels after this and make another call," Washington said. "We've got to leave him in the process. If we think he's ready, we'll make a call. If that's tomorrow, we'll make it."

Harrison gives take on 2013: Left-hander Matt Harrison, who was shut down with back issues on Tuesday, had a description for a 2013 season that saw him make two starts to begin the season, followed by two surgeries.

"It's been forgettable," Harrison said Wednesday. "At this point I just want to clear my head."

Harrison will take at least a few weeks before he picks up a baseball. He said he was 100 percent before he began his rehab assignment -- he made three starts -- but once he got going, he started feeling weakness in his back, then soreness in his elbow as he changed his arm slot.

"It just hasn't had enough time to heal yet," Harrison said. "My arm was dragging and my rhythm wasn't right."

Harrison expects to be fully healthy and ready for spring training.

Blackley adds protection: The addition of left-hander Travis Blackley gives the Rangers protection for their pitching staff, and also gives them a guy who had success against them.

Blackley, who pitched for Triple-A Round Rock, has eight wins in the major leagues, four of them against the Rangers.

"He's been a big league starter and had some success, especially he's had success against us," Washington said. "The way our starting pitchers have been dropping, we were lucky to get a guy like that. He does give us some insurance."

Ross makes progress: Left-hander Robbie Ross has struggled to get out left-handed hitters, but he retired both that he faced in the ninth inning on Tuesday night with the Rangers trailing 5-1.

"We gave him chance with no pressure to get it done, and he got it done," Washington said.

Martin talks Cuban slugger: The Rangers have been mentioned as one of the teams that could be heavily involved in the bidding for Cuban slugger Jose Abreu, who according to reports has defected and is currently in Haiti.

The 26-year-old first baseman/DH has a fan with the Rangers: fellow countryman Leonys Martin, who said Wednesday that Abreu has the best power of all the Cuban players. "Big power," Martin said.

Bidding for Abreu is supposed to take place around the time the free-agent season opens in November.

Tepesch closer to mound: Right-hander Nick Tepesch said Wednesday that he expects to throw from a mound some time in the next week. He has been throwing for the last week from 120 feet.

Tepesch has been on the 15-day disabled list with right elbow inflammation since July 7.