Royals 2012 first round pick pitcher Kyle Zimmer was recently promoted to AA Northwest Arkansas to work on building up his innings after missing the first month with a shoulder issue. He made his debut with the Naturals last night, but left after just one inning and 22 pitches, only eleven of which were strikes.

Naturals manager Vance Wilson said he didn't know what was the matter with Kyle Zimmer, but he was slated to go 3 innings. — paul boyd (@nwapaulb) May 18, 2016

This morning, on 610 KCSP, Dayton Moore addressed the pitching prospect's injury woes.

Dayton Moore says about Kyle Zimmer "it's been a tough road for him." Cites fatigue & that his shoulder "hasn't been responding." #Royals — Josh Vernier (@JoshVernier610) May 18, 2016

For now, #Royals are not labeling any specific injury to prospect Kyle Zimmer, who left after one inning last night. Just listed day to day. — Jeffrey Flanagan (@FlannyMLB) May 18, 2016

Since the Royals took him fifth overall, Zimmer has been beset by injuries. He had an elbow cleanout in 2012, then missed nearly all of the 2014 season with a lat injury. After that season, he had a shoulder debridement of his rotator cuff and labrum. He has pitched just 222 1/3 innings in just over four seasons. He has been a consensus Top 100 prospect in baseball and is considered the Royals top pitching prospect with electric stuff, but cannot stay healthy enough for a full season.