The Phillies recalled Hammer from Triple-A Lehigh Valley on Saturday, Matt Gelb of The Athletic reports.
Hammer has a 1.74 ERA and 1.14 WHIP in 20.2 relief innings with the IronPigs this season. He last appeared in the big leagues in 2019, appearing in 20 games for the Phillies and posting a 3.79 ERA. Odubel Herrera (ankle) was placed on the injured list in a corresponding move Saturday.