The Royals optioned Hernandez to Triple-A Omaha on Thursday.
Hernandez didn't make his season debut for the Royals until last week after recovering from a shoulder injury and has allowed one run with a 1:3 K:BB over 2.2 innings covering four appearances. He'll likely be back with the big club sooner rather than later, but the Royals needed to free up a roster spot for Daniel Lynch, who was called up from Omaha to make a spot start Thursday versus the Twins.