The Royals optioned Rivera to Triple-A Omaha on Wednesday.
Kansas City is expected to begin the season with a four-man bench that includes two outfielders (Kyle Isbel and Edward Olivares) and a first baseman/designated hitter in Ryan O'Hearn, which left no room for Rivera as a utility infielder. The lack of a versatile infielder off the bench shouldn't prove too consequential for the Royals, as everyday players Whit Merrifield, Nicky Lopez, Adalberto Mondesi and Hunter Dozier are all capable of playing at multiple positions.