 Mazzaro was 10-17 with a 4.72 ERA in 41 career Major League appearances, including 35 starts, for the Athletics in 2009 and 2010.Bruce Chen began the year with a 4-1 record and 3.59 ERA in seven starts for the Royals.Chen was placed on the 15-day Disabled List on May 11 (retroactive to May 6), with a strain, and right-handed pitcher Vin Mazzaro was recalled from the Omaha Storm Chasers.