A timetable for Mather's return is unclear, but it is possible that the operation, his second since he sustained the injury last year, will sideline him for the remainder of the season.
Mozeliak did not fully declare that Mather is done for 2009, but he allowed that "the likelihood is yes."
Mather injured the wrist on Sept. 1 of last year and underwent surgery soon thereafter. He struggled in Spring Training and got off to a slow start at Triple-A Memphis, and in early May was placed on the disabled list in order to receive treatment in hopes of avoiding further surgery.
Upon his immediate return, Mather hit well, but he soon slumped again. The condition proved too much to overcome, and he had a second operation on Monday.
"He just was having trouble getting the strength back that he felt he needed to really swing the bat with authority," Mozeliak said. "It's unfortunate, but it was time that we had to make that decision."
Matthew Leach is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.