Manager Kevin Cash said Friday the American League saves leader had the operation in Philadelphia. There is no timetable for his return, but Cash says the team will have a better idea after the first four weeks of recovery.
Cash added that the "core muscle" injury had been nagging Boxberger this spring and he needed to take care of it.
"It was very unique that it wasn't really causing pain," he said. "Had we not got it fixed, then it nags for a long time. Box was in good spirits, and (it was) a very successful procedure."
In 2015, Boxberger had 41 saves in 47 opportunities. The 27-year-old right-hander was 4-10 with a 3.71 ERA. He was an All-Star for the first time.
"It's a blow because he's so valuable to our team, especially at the back end of a game," Cash said. "We have a number of guys that could try to fill that void for the first month of the year. We will close how it matches up and who is ready to pitch on each given night."