Diaz went 1-for-4 with a solo home run in Thursday's 6-3 loss to the Athletics.
Diaz cracked his first homer of the season to the opposite field in the eighth inning to cut into the Royals' deficit, though they were unable to complete a comeback. The 35-year-old has seen limited playing time since being called up April 19 to serve as the team's third catcher but has produced when called upon, going 4-for-11 (.364) with a homer, two doubles, three RBI, two runs and a walk across four games.