Mike Morris puts this in terms that even I can mostly understand:
http://fishduck.com/2016/01/coachs-comments-brady-hoke-brings-the-4-3-defense-whats-up-with-that/
http://fishduck.com/2016/01/coachs-comments-brady-hoke-brings-the-4-3-defense-whats-up-with-that/