"He's been sent back to Kansas City, but it's not a serious thing. I think he's slated to go out on [Minor League] rehab next week sometime," manager Ned Yost said.
Cain began the season as the Royals' starting center fielder and his troubles began in the fifth game on April 10 at Oakland, when he banged into the wall while making a catch. He went on the disabled list with a left groin strain and later was sent on a rehab assignment with Double-A Northwest Arkansas.
In just his third game with the Naturals on April 24, Cain suffered a left hip flexor tear when he broke back for a fly ball. At the time, Cain was told he'd be out four to eight weeks. He's been at Surprise ever since and has missed 53 of the Royals' games.
"I forget how long it has been, I didn't realize that it's been that long," Yost said.