The Giants recalled Walton from Triple-A Sacramento on Sunday and placed him on the 60-day injured list with right shoulder inflammation, Susan Slusser of the San Francisco Chronicle reports.
Walton had previously been on Sacramento's 7-day IL with an unspecified injury, but he played in three rehab games with the Giants' rookie-level Arizona Complex League affiliate this week. The 28-year-old suffered an apparent setback during the rehab assignment, however, and he'll now be sidelined for the rest of the season as a result. By calling up the injured Walton and placing him on the 60-day IL, the Giants were able to open up a spot on the 40-man roster for catcher Patrick Mazeika, who was claimed off waivers from the Mets on Sunday.