In a rehab assignment with Nashville and Class A Stockton, O'Flaherty did not allow an earned run, walk a batter or record a strikeout in two innings of work (two appearances).
Castro did not appear in a game during this stint with the A's, and he has not allowed a run in three of his four relief appearances with Oakland. He has a 3.00 ERA overall, yielding six hits in three innings of work.
Joey Nowak is a reporter for MLB.com. Follow him on Twitter at @joeynowak. This story was not subject to the approval of Major League Baseball or its clubs.