Harrison, an 18-game winner in 2012, was the Rangers' Opening Day pitcher last season but made just two starts before being diagnosed with a herniated disc in his lower back. He underwent surgery on April 23 and again on May 1, and did not return the rest of the season. He also had surgery for Thoracic Outlet Syndrome on his right shoulder on Sept. 9.
There was a time last year when Harrison felt he might not make it back. In addition to the two back operations, he was shut down in August after three outings on medical rehab assignment when the back wasn't responding the way he expected.
"The back not being 100 percent … I started wondering if this was something I could overcome," Harrison said. "We shut it down at the end of last year and just stayed focused … stayed focused on getting healthy. But at that point I was seriously wondering if I was going to get back.
"It was tough. I had signed a long-term [five years, $55 million] and I wanted to prove I was worth the time and the money to pitch at this level. It was tough after what I had done in my career, to be shut down with back surgery … it was hard to get through it."
Harrison made three starts on rehab this month and the last one convinced the Rangers he is ready. Pitching for Double-A Frisco, Harrison threw eight scoreless innings while allowing three hits and a walk while striking out five. He threw just 86 pitches.
"I feel 100 percent," Harrison said. "I feel like I did before the injury. The big thing is I just can't go out there, take a deep breath, relax and say, 'I'm back.' That's not going to help anybody. I need to focus on what I needed to do. Be aggressive and attack. I think my mind frame is in the right place."
Manager Ron Washington said Harrison won't be on a set pitch count. Washington said common sense will dictate how deep Harrison will go in the game.
"He's ready to go, he just has to control his emotions," Washington said.
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.