He experienced discomfort while pitching in extended spring training, and was examined by Brewers head physician Dr. William Raasch, who performed an ulnar nerve transposition Tuesday. Raasch also performed Kirby's Tommy John surgery on Sept. 1, 2015.
MLBPipeline.com ranks Kirby 26th on its list of Milwaukee's top prospects.
Guerra nearing game action
Brewers Opening Day starter Junior Guerra took part in agility drills at Miller Park on Monday while the rest of the team was off, and will throw another batting practice Wednesday.
If that goes well, the Brewers would send Guerra out on a Minor League rehab assignment likely to span multiple starts. Guerra has been on the disabled list since straining his right calf on a bunt in the third inning of the Brewers' Opening Day loss to the Rockies.
"He's doing great," Brewers manager Craig Counsell said. "He'll have a pretty extensive session in here [on Wednesday]."
'Bigger than baseball'
Brewers starter Jimmy Nelson had planned to get breakfast over the weekend with the Pirates' Jameson Taillon, but their plans were cancelled when Taillon learned he would require surgery for suspected testicular cancer.
After Taillon underwent the procedure on Monday, Nelson sent a text message of support.
"He's been through a lot," Nelson said. "Hernia surgery, Tommy John, [Hernan Perez] hit him in the head [with a line drive]. He's had his battles, but he always has a good attitude going into them. That's always refreshing. He doesn't get too down. He doesn't get too negative about any situation. That's something I think everybody can take from this."
Nelson and Taillon live in the Houston area during the offseason, and work out in a group that also includes Cardinals pitcher Michael Wacha.
Taillon's situation was another reminder for Nelson that there is more to life than baseball. He is also friends with the Rockies' Chad Bettis, who underwent surgery for testicular cancer in November and was mounting a comeback in Spring Training when he learned his cancer returned.
Adam McCalvy has covered the Brewers for MLB.com since 2001. Follow him on Twitter @AdamMcCalvy, like him on Facebook and listen to his podcast. This story was not subject to the approval of Major League Baseball or its clubs.