Holmberg, 23, is one among several competing in camp for the two open spots in Cincinnati's rotation. To be under consideration is a testament to his efforts to make a course correction in 2014.
Acquired in December 2013 from the D-backs in a three-team trade that sent catcher Ryan Hanigan to the Rays, Holmberg came to Reds camp overweight and then was limited to one spring appearance with a sore right shin. In April, he spent time on Triple-A Louisville's disabled list with left shoulder tendinitis.
When he came to the Majors for a pair of spot starts, Holmberg was pummeled and had an 18.56 ERA. Back again as a September callup, however, he turned it all around and had a 1.90 ERA over his final four games, including three starts.
"He wasn't in shape when he got here, he gained some weight," Reds manager Bryan Price said. "I don't know if his arm was in great shape or not. He addressed it immediately. We had to talk about it and address it. To his credit, not only did he make an immediate adjustment, he learned his lesson and came into camp this year in great shape.
"He's throwing the ball beautifully. Most of the guys on the board have thrown the ball very well this spring. He's throwing the ball as well as anybody, from what I've seen of him. He looks like the guy we traded for."
Holmberg admitted there were times early last season where he became lackadaisical, and he realized he had to change.
"It was more of losing focus on the mound," he said. "When you don't execute pitches in the big leagues, you get hit. You have to make better pitches. I definitely learned to do that toward the end of the year."
Holmberg said he's dropped 30 pounds since last spring -- 15 during the 2014 season and 15 more in the past offseason.
"I felt like I performed closer to what I'm capable of at the end of the year," Holmberg said. "That's who I want to be -- a strike-thrower that gets quick outs and moves through games."
Mark Sheldon is a reporter for MLB.com. Read his blog, Mark My Word, and follow him on Twitter @m_sheldon. This story was not subject to the approval of Major League Baseball or its clubs.