Walker joins the Ducks with eight seasons of Major League experience split between five different organizations (Mets, Giants, Devil Rays, Phillies, and Nationals). He last pitched in the big leagues for the Nationals in 2010, posting a 1-0 record with a 3.57 ERA in 24 games. For his Major League career, the San Francisco native has a 23-18 record with a 4.23 ERA and 34 saves in 286 games.

The 35-year-old compiled a 1.50 ERA and five saves in 12 games with St. Paul, helping the Saints to the American Association Championship Series. In 11 minor league seasons entering 2011, he totaled a 45-45 record with a 3.83 ERA in 221 games (130 starts). Walker was originally drafted by the Mets in the second round of 1997 amateur entry draft.