Some good specifics in this article on Banker's D and what the principles are.
http://www.omaha.com/huskers/react-attack-banker-s-husker-defense-aims-to-cash-in/article_0dd8e96c-4a4d-5984-b984-9417f8f7afff.html
http://www.omaha.com/huskers/react-attack-banker-s-husker-defense-aims-to-cash-in/article_0dd8e96c-4a4d-5984-b984-9417f8f7afff.html