Duffy is battling shoulder tightness, Jeffrey Flanagan of MLB.com reports.

EDGE Analysis

Manager Ned Yost didn't seem particularly concerned about the issue, calling it "normal spring stuff," but the fact that Duffy's 2018 campaign was cut short in early September by similar issues does make the injury somewhat worrisome. Duffy will be backed off temporarily. If he's able to get back on the mound soon, he'll still have time to build up for Opening Day, but an extended absence could make a stint on the injured list likely.