I was actually thinking about doing Madden style defense introduction, help people to pick the right formation, and play on defense based on what personnel the offense brings out.
By the way, if you play Madden, and pick your defense before the offense picks their play, don't. You should have a general idea of what you want to run, the most important part is the formation you pick, mostly do you want 4 DBs, or 5. However if they come out in the spread, and you picked 4-3 or 3-4. You're probably screwed.
Moral of the story. Defensive personnel is entirely dependent on offensive personnel.