Dr. Saturday recently broke down some of the zone-blitzes Utah used against Alabama in their bowl game. It's great analysis; check it out. For a bit more on pass protection and zone-blitzes generally, check out my article here. Also, Bob Davie wrote a worthy article for ESPN about zone-blitzes a few years back. Read all that and come back here: I want to highlight a few quick aspects of the most common zone-blitzes or fire zones. I'll have to leave a more in depth discussion for another time.
Below is a diagram of one of Nick Saban's most common zone-blitzes:
This is very typical. One thing Matt did a great job of breaking down with the Utah article was in his discussion of how the Utes crossed up 'Bama's protections. But it's worth noting the constraints the zone-blitz puts on the defense: namely, the number of coverages you can viably use. Occasionally, in the NFL, some teams zone blitz with a mere Cover 2 or two-deep zone behind it. The Ravens get away with this sometimes with Ed Reed, but it is dangerous -- with all your defensive movement you don't get good jams on the receivers and you too often will let receivers run free in the deep voids.
So by far the most common coverage behind a zone-blitz is a three-deep three-under coverage. Obviously, that can leave wide open spots underneath, but that's still part of the zone-blitz philosophy. As some defensive coordinators say, with so much three-deep, it is actually a conservative approach. And it is one reason why zone-blitzes are so common on third down -- defenses get good opportunities to cross up the pass protection while forcing completions to be made underneath where guys can make a quick tackle short of the first down. This is a favorite strategy of Jim Johnson of the Philadelphia Eagles: there's nothing wrong with giving up a five yard completion on third and nine. (Further, most progressions have the quarterback read long-to-short. By taking away long and forcing short the defense gives itself another few moments to get to the quarterback before he can release the ball.)
Below is a video clip (courtesy of HueyTube) of LSU running basically the zone-blitz diagrammed above.
On the first play in the clip, notice the way the three linebackers appear to attack just before the snap, but then the left outside linebacker (lined up to the short side of the field) drops into coverage, as does the the left defensive end. The strong safety comes up to play the flat and seam areas, and the two corners and the safety drop back into a simple three-deep. And Tennessee actually gets a completion, largely because the linebacker who probably ought to have been in the middle of the field follows the tight end on a short drag route and thus exposes the middle to an in-breaking receiver. (The linebacker should have passed him off to the defensive end who had dropped out; they end up defending the same area leaving the middle wide open).
On the second play LSU is in the same zone-blitz, with three deep. This time Tennessee keeps it simple and throws an out route against the soft outside coverage. Throwing away from defenders is often a solid strategy -- not that it is always easy to identify when there's a zone-blitz on.
Next, briefly, take a look at the clip below of the New York Giants running some fire zones. (Note: the best way to watch this is to watch and rewind several times, watching different players. You can barely see the ball anyway so watch the safeties, linebackers, line, etc. each successive time you replay it.)
In the first clip against the Cowboys, you'll see the exact same coverage -- three-deep, three-short -- except they have changed who does what to further disguise things (hey, it's the NFL now). Now you have a cornerback blitz from the weakside of the formation (and short side of the field), and the three-deep look, instead of being comprised of the two corners and safety, is now in the form of what is called a "cloud" rotation: the corner and two safeties rotate over to create the three-deep coverage. The overload blitz now comes from the short side of the field rather than the wide side as with LSU, and the other linebackers rotate over to fill up the underneath zones. It's really just the same thing, just a different look. And, again, in the NFL your guys can do more. Not only can your linemen drop into coverage, but your secondary can blitz and get to the quartberback while apparently lined up over a receiver.
And, another advantage with the NFL over college comes with the techniques involved. Around the 1:30 mark of that clip is another, rather traditional fire-zone. Atlanta throws about a six or seven yard hitch for a completion. But note the look from the secondary: the cornerback is lined up over the receiver as if he is in press man, but instead he bails -- after the snap -- into the deep-third, thus giving up the underneath completion. Few college or high schools will put cornerbacks responsible for deep thirds of the field up on the line of scrimmage so close to a receiver. Again, it's the NFL. Here, there is little fault you can blame on the offense: kudos to the quarterback and receiver for identifying the coverage despite the disguise.
Finally, motion is still a good way to reveal whether a defense is in man or zone, particularly when the motion changes the strength of the formation. (Though teams are certainly much better at disgusing their coverages even with motion or shifting.) If the defender runs across the field with the receiver, it is probably man. If they sort of "bump over," it's probably zone. And if it is man, well, then maybe you're getting better matchups.
More to come on blitzing, pass protection, and zone-blitzes throughout the offseason.