According to Yost, Cain has been playing catch and throwing, but he was only allowed to swing a bat starting Monday. The Royals have continued to look for progress with Cain's hand strength, which has shown "at least 50 percent" improvement over the last two days.
Cain had reportedly been playing through the injury for around two weeks before the Royals decided to give him time off to recover, and the inflammation and pain have taken longer to subside than had been anticipated.
"It's going to be day-to-day," Yost said. "You can ask every day, but he's getting better every single day."
Cain had been hitting .287/.336/.409 with nine homers, 56 RBIs and 13 stolen bases in 102 games before he was pulled from the lineup.
"The good thing is, hopefully, when he comes back, he's going to be a lot stronger than he was before all this happened," Yost said.
Paulo Orlando earned his fifth straight start in right field on Monday, while Jarrod Dyson continued to start in center.
Do-Hyoung Park is a reporter for MLB.com based in Minneapolis. This story was not subject to the approval of Major League Baseball or its clubs.