Excerpt from the Headache Offense complete package:
In man, they need to cover the receiver and keep their eye on him instead of the QB or the ball. In zone they read the QB and try and anticipate where the ball is going to go and go for plays on the ball.
The main thing about learning to play zone is practicing as a group. They just need to know approx where their zone is and to practice anticipating the ball. Also, as soon as the ball is in the air everyone should immediately swarm to the ball. Since everyone is watching the QB they should all be right in the area of the ball by the time the receiver catches it (if the zone player fails to make a play on it). Does that make sense? It’s all anticipation and reaction, as quick as possible. Do coach the outside corners to be aware of a possible lateral after the catch. If there’s no receiver in the area for a lateral he swarms like everyone else. If there is he should still come to teh ball but anticipate the lateral, stay in the pitching lane and try and intercept the pitch. It’s easy for him to get lulled after a while though and the one time they do lateral it he’s asleep on the job and gets beaten for a big gain.
The deep safeties keep everything in front of them and should not cross the receiver to make a play on the ball unless he is 110% sure without a shadow of a doubt he is going to pick it off. There is no excuse for him to ever be underneath a receiver when the receiver catches the ball, and he should always be deep enough to get to a receiver who has caught the ball and make the tackle. The outside corners need to know that they should always be outside of the most outside receiver. There should NEVER be any receiver between him and the sideline! He has outside contain, he keeps everything inside of him. On option plays he has the pitch always and he has to always be aware of the lateral. If there is a receiver running an out route he should anticipate the ball and start getting in position to make a play (unless there is a receiver that is more threatening to the outside).
The corners should be deeper than the two inside zone defenders. They should be more concerned about the deep out and the corner route than the 5 yard out-route or trying to intercept a 5 yard button hook. The outside routes take longer to get the ball to so he will have time while the ball is in the air to come up and make a play on the receiver. But 5 yard outside routes are hard to complete, easy to tackle and prevent YAC, and aren’t that damaging to a defense. It’s okay to let them have those 5 yard plays as long as you can keep them to just 5 yards. The corner should be more concerned about being in position on a deep out or corner pattern because it is hard for the safety to cover them. The only real catch to that is the swing pass to the running back. If they are killing you with that you may need to have your corner come up closer to the line.