"He wasn't as effective as we'd like him to be," Rangers manager Ron Washington said. "We haven't totally given up on Robbie being a starter, but we're in a position where we have to get our players in a position to succeed."
Baker was with the Twins from 2005-11 and made 159 starts with a record of 63-48 while tallying a 4.17 ERA before his career was derailed by Tommy John elbow reconstruction surgery. He made three starts for the Cubs last year before signing a Minor League contract with the Rangers in Spring Training.
Baker was 4-1 with a 3.32 ERA in six starts at Triple-A Round Rock before he was called up to the big leagues. His only outing with the Rangers was on May 7, when he pitched 5 1/3 innings in relief against the Rockies. He allowed two runs.
"He's got experience," Washington said. "He's been out there trying to get 27 outs before. We'll give him a shot. Where we are is giving guys opportunities so he'll get an opportunity."
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.