The Kansas City Royals optioned Vin Mazzaro to Triple-A Omaha on Thursday.
Mazzaro gave up three runs and four hits in 2 1-3 innings Tuesday.
The move was announced before a game with the Seattle Mariners. Rookie right-hander Will Smith was recalled from Omaha and started.
Mazzaro is 3-3 with a 6.12 ERA in three stints with the Royals this season, allowing 44 hits and walking 12 in 32 1-3 innings.