DETROIT -- Right-hander Kyle Zimmer, the Royals' first-round choice in the 2012 First-Year Player Draft and ranked first among Kansas City prospects by MLB.com, has been shut down for the season after leaving his start for Northwest Arkansas on Wednesday night because of shoulder stiffness.
"Kyle has some minor shoulder irritation and has reached his innings threshold for the season, so he will no longer pitch in 2013," said Royals director of player development Scott Sharp. "He is returning to school for the fall semester to rest and knock out some classes, and will return ready to go in 2014."
Zimmer pitched 108 1/3 innings this summer for Double-A Northwest Arkansas and Class A Wilmington. He had a combined record of 6-9 with a 4.32 ERA in 22 starts. He piled up 140 strikeouts against just 36 walks.
For Northwest Arkansas, he made four starts with a 2-1 record and a 1.93 ERA.
Zimmer, 21, underwent what the club termed minor elbow surgery last August, ending his first pro season. In 2012, he pitched in nine games for two low-level clubs, with a 3-3 record and a 2.04 ERA over 39 2/3 innings.
Dick Kaegel is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.