McFarland (1-0) got the win against the Orioles on Sunday, firing a perfect eighth inning during which he recorded two strikeouts.
The Athletics acquired McFarland from the Dodgers in exchange for cash considerations and selected his contract from Triple-A Las Vegas.
McFarland signed a minor-league contract with the Dodgers on Friday that includes an invitation to spring training, Fabian Ardaya of The Athletic reports.
McFarland signed a minor-league contract with the Orioles on Saturday, Roch Kubatko of MASNSports.com reports.
McFarland cleared waivers and was outrighted to Triple-A Syracuse on Monday.
The Mets designated McFarland for assignment Friday, Anthony DiComo of MLB.com reports.
The Mets selected McFarland's contract from Triple-A Syracuse on Monday, Anthony DiComo of MLB.com reports.
The Mets reassigned McFarland to minor-league camp Sunday.
McFarland signed a minor-league contract with the Mets on Tuesday, Michael Mayer of MetsmerizedOnline.com reports.
McFarland re-signed Tuesday with the Cardinals on a minor-league contract.