The Athletics recalled Ferguson from Triple-A Las Vegas on Wednesday.
Ferguson was one of the club's better relievers last season, but he was sent down in June following a rough stretch in which he yielded 10 runs over four appearances. The 31-year-old seemed to get back on track at Las Vegas, permitting just one earned run with an 11:3 K:BB over 10 innings. Ferguson could pitch his way back into leveraged situations in an unsettled bullpen, though that probably won't happen right away.