The 27-year-old was 1-4 with a 6.75 ERA in eight starts and seven relief appearances with the Phillies in 2006, 2010 and this year. He didn't allow a run in four relief outings this year.
Mathieson also has a 32-37 record with a 3.75 ERA and 34 saves in 96 starts and 104 relief appearances in the minor leagues.
The move was announced Tuesday.
