The 28-year-old Mather can play first base, third base and all three outfield positions. This past season, he got into 36 games for the Cardinals, batting .217 with three RBIs.
Mather made the Opening Day roster for the first time in his career but was optioned to Triple-A Memphis in late May. He returned to the majors when the rosters expanded in September.
His best season in the majors was 2008, when he batted .241 with eight homers and 18 RBIs for St. Louis.