Ziegler (knee) threw off a mound Tuesday for the first time since undergoing microfracture surgery in September, mlb.com's Steve Gilbert reports. While Ziegler shouldn't quite be considered a lock for Opening Day, the Diamondbacks expect him to be ready by that time. The side-armer figures to open 2015 in a setup role, but he could be in the mix for saves if Addison Reed (general soreness) has another rocky season.