Baker, who has crushed left-handed pitching this season, will be in the starting lineup with the Orioles starting southpaw Wei-Yin Chen, manager Ron Washington said before a team workout Thursday afternoon at Rangers Ballpark in Arlington.
"We'll put him back in there against them," Washington said of using Baker against left-handed starters.
Gentry also is an option to start Friday's game, though Leonys Martin had become the Rangers' everyday center fielder before Gentry went on the 15-day disabled list with a non-displaced fracture in his right hand.
Baker was 2-for-11 in three games with Frisco and said Friday he has no issues with his right thumb, which he sprained in a high-five that went wrong back in June.
Gentry was 3-for-13 with all of his hits coming in Frisco's doubleheader Thursday. He had two hits in the second game.
Rotation switch: The Rangers shuffled the rotation for their first series against Baltimore, with right-hander Ross Wolf now slated to start Saturday's game and left-hander Martin Perez going on Sunday. Derek Holland will start Friday's series opener.
The Rangers made the switch to break up their two left-handed starters, Washington said.
Yu Darvish (strained back muscle) will come off the disabled list Monday and start the opener of a four-game series against the New York Yankees. Darvish threw a bullpen Thursday and the Rangers said that it went well. Right-hander Alexi Ogando (shoulder inflammation) will start Tuesday's game provided his rehab start goes well Thursday night for Triple-A Round Rock.
Berkman update: Designated hitter Lance Berkman (left hip inflammation) returned with his teammates Thursday but was not on the field for the team workout, spending his time in the training room receiving treatment.
Berkman has been on the disabled list since July 7. The Rangers are still hopeful he can come back and help in the final 67 games. Berkman hasn't hit a home run left-handed since May 11, a stretch of 38 games before he landed on the DL.
"We could use another bat in the lineup," Rangers general manager Jon Daniels said. "Lance is one of them. In Lance's case, it's been physical. We feel like we could use more offense. We'd like Lance to be a part of that equation. I still think that's a possibility."
Busby, Nadel off for a few days: Steve Busby will miss Friday and Saturday for personal reasons, so Tom Grieve and Mark McLemore will do the TV broadcasts. Grieve will handle the play-by-play after handling a few innings on the Rangers' final road trip to get prepared for Busby's absence.
Rangers radio play-by-play man Eric Nadel will miss the opening home series against the Orioles because of vacation time that is in his contract with the club. Matt Hicks and Mike Peasley will handle the radio broadcasts.
Harrison ahead of schedule: Left-hander Matt Harrison, who had two back surgeries early in the season, threw his first bullpen session (25 pitches) Thursday and said that it went well and that he is ahead of schedule by a week.
Harrison is targeting beginning a rehab assignment around the first of August, which could put him back in the big leagues by late in the month.
Transactions: The Rangers optioned RHP Wilmer Font and C Robinson Chirinos to Round Rock to make room for Baker and Gentry, who will be activated Friday. Also, left-handed pitcher Brad Mills has been granted his release from the organization in order to sign a contract with the Orix Buffaloes of Nippon Professional Baseball’s Pacific League.
Rookie pitchers throw: Nick Tepesch, on the disabled list with right elbow inflammation, and Justin Grimm, who left his last start with forearm stiffness, both threw 90 feet on Thursday.