Top Kansas City pitching prospect Kyle Zimmer underwent minor right shoulder surgery in New York City on Tuesday.
Ranked second among Royals prospects, Zimmer had damaged tissue in his labrum and rotator cuff of his throwing arm removed by Mets medical director David Altchek, according to the Kansas City Star.
The team said last Monday it was going to cut the 2012 first-rounder's Arizona Fall League campaign short after only three starts. Zimmer reaggravated his shoulder and was pulled from his outing for precautionary reasons two days earlier after just one inning.
"He had some soreness in his shoulder, and rather than let him pitch through it, we just took him out of the game," Royals assistant general manager J.J. Picollo told MLB.com at the time.
Injuries are nothing new for MLB.com's No. 47 prospect, who had bone chips removed in his elbow two years ago and was shut down with elbow tendinitis last season. Shoulder injuries forced him to miss the start of the 2014 campaign and the same problems resurfaced after just six starts upon his return to the mound in May.
The 23-year-old struck out 15 batters and issued four walks over 9 2/3 innings in three AFL starts with Peoria, posting a 2.79 ERA. He appeared to be back on track when he fanned 11 Desert Dogs over five two-hit frames in his second outing, but he faced just three batters in his following game five days later.
"All the MRIs he's had done, there's been nothing structurally wrong," Picollo told the newspaper Monday afternoon. "So that's been a mystery with this. Just in talking to our doctors, it might be time just for an exploratory scope, just to see what's in there. Just because it's been a little bit of a mystery. Maybe that will clarify something for us. Maybe that will find something that the MRIs just didn't show."
The exact timetable for Zimmer's recovery is not yet known, although it is possible he will be able to begin rehabilitating his shoulder before the end of the year.
Ashley Marshall is a contributor to MiLB.com. Follow him on Twitter @AshMarshallMLB.