Eric O'Flaherty (elbow) threw a successful bullpen session in front of Athletics manager Bob Melvin on Saturday.
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The A's believe that he could be cleared to face live hitters by the time they return from their next road trip. He remains on track to rejoin the A's bullpen at some point in June, making an already strong bullpen even more dominant.
Pirates optioned C Tony Sanchez to Triple-A Indianapolis.
The 25-year-old backstop acquitted himself well during his brief stay with the Pirates, hitting .333/.333/.389 with four RBI in 18 at-bats. He'll continue to function as organizational depth and will return to the Pirates should they suffer any injuries behind the dish.