The Giants released McKenna on Saturday.
McKenna cleared waivers Friday and was sent outright to Triple-A Sacramento, Shayna Rubin of the San Francisco Chronicle reports.
The Giants designated McKenna for assignment Tuesday, Alex Pavlovic of NBC Sports Bay Area reports.
McKenna went 0-for-1 with a stolen base and a run scored in Saturday's 7-2 extra-inning win over the Mets.
The Giants added McKenna to the 26-man roster Tuesday.
The Giants claimed McKenna off waivers from Baltimore on Saturday, Robert Murray of FanSided.com reports.
The Orioles designated McKenna for assignment Monday.
The Orioles selected McKenna's contract from Triple-A Norfolk on Friday.
McKenna cleared waivers and was outrighted to Triple-A Norfolk on Sunday, Cordell Woodland of 105.7 The Fan Baltimore reports.
The Orioles designated McKenna for assignment Thursday.