The Double "A" gap blitz
If you're unfamiliar with gaps, the "A" gap is the space between the Center and Guard on either side. When you talk about bringing a Double "A" gap blitz, it means you are bringing two rushers through this area. Every team has this in their defensive playbook, and it is usually an effective way to take down the quarterback...why? Because it creates a precarious situation in which the Center and Running Back have to be perfect in picking up each blitzer. Often times the Center and the back will bite on the same rusher while a delayed rush comes through free.
Is this a "green dog" concept? No. When a linebacker has coverage responsibilities on the running back, he will read the situation. If the back stays in, the linebacker has a "green light" to rush the quarterback. This is called a "green dog." With the double "A" gap blitz, those blitzers are coming regardless.
Let's take a look at the action.
Colts are in 11 personnel from the shotgun. Broncos counter with 4-2-5 nickel. Your DB's are Harris Jr. and Aqib Talib (outside) and Bradley Roby (inside). Your linebackers on the play are Brandon Marshall and Nate Irving. As a quarterback you want to first identify the safety alignment and see if that tips the coverage. Rahim Moore is deep center field which indicates the coverage could be Cover 1, possibly Cover 3. Luck will learn more at the snap when he sees the reaction of the DB's. It's all about limiting your options to what the defense isn't doing in order to take educated guesses on what they are doing. (That's Manning passing offense in a nutshell).
Ok pretty straightforward. Nate is the first blitzer through the "A" gap and he gets there before Luck has a chance to notice it. Let's see what we can gather from another view.
All-22 view 1
Did you see that? Brandon Marshall is the one who "faked" the blitz before the snap. This got Luck to identify Marshall as the "MIKE" which slid the protection in order to pick him up. I'm not sure what the back is doing. He fires out fast as if he's releasing to a route...but he also reaches back for Marshall.
All-22 view 2
From this view you can see it plain as day. The RB whiffed on the initial rusher (Marshall) and it appears as if the center never even cares about picking up Irving. This confirms what I thought about Luck shifting the blocking assignments presnap. The last little tidbit to uncover? 3-tech Sylvester Williams loops around and takes his blocker to the right opening a larger hole for Irving to rush through.
Good design and execution. If I'm Luck, I have to identify the off coverage at the right side and throw hot over there. That will do it for the first installment of Denver Broncos X's and O's. I'll try and have one of these done everyday until we've examined all our sack data.