Oaks made the Giants' 60-man roster.
Oaks cleared waivers and was outrighted to Triple-A Sacramento on Friday, Kerry Crowley of The San Jose Mercury News reports.
Oaks was designated for assignment by the Giants on Thursday, Amy Gutierrez of NBC Sports Bay Area reports.
Oaks was claimed off waivers by the Giants on Tuesday.
Oaks (hip) was reinstated from the 60-day injured list and designated for assignment Tuesday, Jeffrey Flanagan of MLB.com reports.
Oaks (hip) started a throwing program Sunday, Jeffrey Flanagan of MLB.com reports.
The Royals placed Oaks (hip) on the 60-day injured list Thursday.
Oaks underwent hip surgery Thursday and hopes to resume baseball activities in four months, Jeffrey Flanagan of MLB.com reports.
Oaks has been shut down with a right hip injury and may require surgery, Jeffrey Flanagan of MLB.com reports.
Oaks was optioned to Triple-A Omaha on Friday.