Oakland Athletics starting pitcher Jarrod Parker will start for the Class-A Advanced Stockton Ports on Thursday, formally beginning a rehabilitation assignment that must expire by May 22, tweets the San Francisco Chronicle's Susan Slusser. Parker is recovering from his second Tommy John surgery, performed in late March of 2014.

Parker appears to be on his way to returning as a starting pitcher, a rare feat for players getting a second Tommy John surgery. He will throw 60 pitches for the Ports on Thursday, tweets MLB.com's Jane Lee. When activated, Parker must either be optioned to the minor leagues or added to the 25-man roster.

The A's acquired Parker during the 2010-11 offseason with Ryan Cook and Collin Cowgill, sending the Arizona Diamondbacks Craig Breslow, Trevor Cahill, and cash considerations. Parker has a career ERA of 3.68 in 384 innings, with 6.4 K/9 and 3.0 BB/9 ratios.