Krol pitched a scoreless inning for Class A West Michigan on Friday. He was still with the Whitecaps in Fort Wayne, Ind., when he got the call that he needed to head back to Detroit early.
"Everything's great. Everything's good to go," Krol said. "It's good to be back."
Krol entered in relief on Sunday night, allowing hits to both batters he faced in the sixth inning before being relieved.
Matt Slovin is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.