Lidge hasn't pitched this season because of elbow and shoulder problems. The move was made before the major-league-leading Phillies opened a 10-game homestand on Friday night against San Diego.
Lidge is 3-9 with 99 saves and a 3.99 ERA in 189 games with the Phillies over the last three seasons. He was a major reason Philadelphia won the World Series in 2008. Lidge was 48 for 48 in save opportunities that year, including the postseason. Lidge isn't expected to return to his closer role.
Baez struggled in parts of two seasons with the Phillies. He was 2-4 with a 6.25 ERA in 29 appearances this year, and was 5-8 with a 5.81 ERA in 80 games overall.