The Pittsburgh Pirates activated shortstop Jordy Mercer from the disabled list on Sunday and placed first baseman Travis Ishikawa on the 15-day DL with a lower back strain. Mercer went on the disabled list on July 20 after spraining the MCL in his right knee and suffering a lower leg contusion in a collision with Carlos Gomez during a game in Milwaukee. Mercer is not in the starting lineup for Sunday night's game against the San Francisco Giants.