KANSAS CITY -- Royals manager Ned Yost said Wednesday that he was shutting down right-hander Brad Keller for the rest of the season because of arm fatigue.

Keller lasted just 1 1/3 innings in a 19-4 loss on Monday to Oakland. He labored during that outing -- his shortest outing in the big leagues -- and walked three straight batters at one point.

“We’re going to finish him up with some side sessions next month,” Yost said. “There’s nothing to gain by throwing him any more this season. He’ll do all his work and finish it off with [pitching coach] Cal [Eldred], working on mechanics so he goes into the off-season feeling good.

“I saw a drop in velo [Monday night]. I saw his arm get real long, which means he’s trying to generate strength. That makes you get long. And his inability to command [was evident]. When you add up the pros and cons, there are no pros and a bunch of cons for him to keep pitching.”

Keller was going to be on a 180-innings limit anyway. He’ll finish this season with 165 1/3 innings pitched, the most of any season for him as a professional. His previous high was in 2015 with 142 innings in the Minors.

Keller said he was fine with the decision and admitted to some fatigue.

“But it’s August,” he said. “It’s the time when everyone is feeling the fatigue. I definitely felt like my arm was dragging a little bit. But we’ll just try to get stronger for next season.

“I think it was just from throwing more innings than ever before. It’s in everyone’s best interest to shut it down.”

Rotation plans

Yost also said he will go with left-hander Danny Duffy on Sunday instead of Saturday as originally planned. Duffy (hamstring) is expected to be activated from the injured list then.

Yost said the Royals wanted to avoid making a roster move Saturday to make room for Duffy. Sunday is the first day of September, when rosters expand.

Right-hander Jorge Lopez will pitch on Saturday instead.

Arizona Fall League Royals

The AFL rosters have been announced, and here are the Royals who will be playing for the Surprise (Ariz.) Saguaros: LHP Daniel Lynch (the Royals' No. 3 prospect per MLB Pipeline), OF Kyle Isbel (No. 8), OF Brewer Hicklen (No. 15), 2B Gabriel Cancel (No. 30), RH Tad Ratliff and LHP Daniel Tillo.