Ziegler underwent microfracture knee surgery Tuesday, Steve Gilbert of MLB.com reports. Microfracture surgery comes with a longer rehabilitation timetable than a standard arthroscopic procedure, but the belief is still that Ziegler should be ready for spring training. The right-hander fell apart after the All-Star break (6.27 ERA, .347 BAA), but still recorded a career-high 29 holds this season, and if healthy, should have little trouble reclaiming the setup job next year.