The Royals have placed right-hander Trevor Cahill on the disabled list with an impingement in his throwing shoulder and recalled fellow righty Kevin McCarthy from Triple-A, tweets Jeffrey Flanagan of MLB.com.

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Cahill’s injury is the latest and most significant setback during what has been a difficult Royals tenure for the 29-year-old. Kansas City made an aggressive move to acquire Cahill, Brandon Maurer and Ryan Buchter in a late-July trade with the Padres, but the success Cahill had in San Diego over the season’s first few months hasn’t transferred to his new setting.

Cahill has made three starts with the Royals and failed to exceed 4 2/3 frames in any of those outings. Overall, he has tossed 11 innings since the trade and yielded 10 earned runs on 18 hits and nine walks, with just six strikeouts, helping to contribute to the Royals’ post-deadline skid. The club has dropped seven of nine this month to fall to 57-56, yet it’s still just one game out of a wild-card spot in a jam-packed American League race.

While it’s unclear exactly how long Cahill will be on the shelf, a shoulder impingement typically requires at least a few weeks to recover, and it comes at an especially inopportune time for the free agent-to-be. All the more troubling is that Cahill missed time earlier this season with shoulder issues.

As they await Cahill’s return, the Royals are likely to turn to righty Jake Junis, who’s currently in Triple-A, to grab the open spot in their rotation, per Rustin Dodd of the Kansas City Star (Twitter link).