Royals prospect Zimmer out for season

Top Royals pitching prospect Kyle Zimmer will undergo surgery and miss the rest of the season, according to MLB.com.

Zimmer, a 24-year-old right-hander, will have Thoracic Outlet Syndrome surgery to relieve pain and discomfort in his arm. Sports Radio 810's Soren Petro first reported the news, which was later confirmed by MLB.com's Jeffrey Flanagan.

The Royals prospect has not pitched since May 17 for Double-A Northwest Arkansas. He was placed on the disabled list on June 2 with what the organization called "shoulder fatigue," the same diagnosis that several months earlier delayed his 2016 debut. He reportedly experienced shoulder issues in mid-March when the Royals optioned him to Minor League camp at Spring Training, but the team was still hopeful he would recover and see time at Triple-A Omaha this year.

"It has been unsettling for him to be throwing 95 [mph] one day and 88 the next," Royals assistant general manager J.J. Picollo told Flanagan. "Now we know why. We're just glad to finally be able to get a diagnosis."

Flanagan said Zimmer is expected to have the surgery "in a couple of weeks" and that he would be ready for Spring Training next year. He said the type of "TOS" is neurogenic, which is the fastest to recover from.

"He should be fine for Spring Training," Picollo said.

The 2012 first-round pick made just three starts this season, the first two with Class A Advanced Wilmington, in which he finished a combined 0-2 with a 1.59 ERA and 11 strikeouts in 5 2/3 innings.

Zimmer appeared in only 64 innings last season, working mostly out of the bullpen, after a lat injury limited him to just six games in 2014. He underwent minor shoulder surgery in October 2014 to remove damaged tissue from his rotator cuff after having elbow surgery in 2012.

Thoracic Outlet Syndrome surgery is the same procedure that shut down Mets ace Matt Harvey on Monday. In Harvey's case, doctors had planned to remove the pitcher's top rib in hopes it would relax muscles in his chest that may have contributed to nerve pain between his shoulder and neck. Harvey's agent, Scott Boras, said the righty would be back in about six months.