Warinner, who will coordinate the running game as Ohio State's co-offensive coordinator/offensive line coach, will be Decker's position coach. Warinner had previously served as the Irish's offensive line coach and running game coordinator.
Decker's de-commitment drops the Irish's recruiting class to 16 members. The 6-foot-8, 310-pounder originally committed to Notre Dame in March.
Ohio State now has 20 commitments for the class of 2012, and four since Meyer took over the Buckeyes.
Notre Dame suffered a de-commitment just a week ago when four-star athlete Ronald Darby (Oxon Hill, Md./Potomac) re-opened his recruitment.