The Giants optioned Matos to Triple-A Sacramento on Wednesday.
Matos will end up as the odd man out of the Giants' outfield after the team claimed Derek Hill off waivers from Texas on Tuesday. Matos slashed .208/.222/.340 with four RBI in 54 plate appearances after his promotion from Triple-A on June 22, and he will be a likely candidate to return to San Francisco should the team's outfield depth be tested later in the season.