Zimmer left Thursday's start for Triple-A Omaha after one inning with right shoulder soreness, Jeffrey Flanagan of MLB.com reports.

The Royals are saying that his removal was precautionary, but given Zimmer's long history of shoulder troubles, this is cause for concern. Zimmer was limited to just three starts last season due to shoulder fatigue and he has thrown fewer than 100 innings total since the start of 2014. The fifth overall pick in 2012, he ultimately underwent Thoracic Outlet Syndrome surgery last year in hopes of putting those issues behind him.

More News
CBS Sports Shop
MLB Opening Day
Our Latest Stories
    Jonah Keri Podcast