Yost said Perez has had several foul balls deflect off his wrist recently, creating soreness.
Though Perez wasn't in the starting lineup for Wednesday night's series finale against the Tigers, Yost said he could play if needed.
"After the MRI he called [catching coach] Pedro [Grifol] and wanted to know if he was playing today," Yost said. "And I was like, 'No, take a day.' He kept saying, 'I can play.' Nah, we don't have to rush him."
Davis throws bullpen
Right-hander Wade Davis, who has been out since last Thursday because of a tight back, threw a bullpen session before Wednesday's game and reported all went well.
"I tried to simulate game conditions and I think [the back] felt pretty good," Davis said. "We'll just see how it feels tomorrow. I think we're pretty close."
Yost said he's not about to rush one of his star relievers such as Davis.
"We're in a position where we don't have to," Yost said of the Royals, who entered Wednesday with a 12-game lead in the American League Central standings.
Jeffrey Flanagan is a reporter for MLB.com. Follow him on Twitter at @FlannyMLB. This story was not subject to the approval of Major League Baseball or its clubs.