Posted by ESPN.com's Kevin Seifert
I've been meaning to follow up on something I mentioned briefly during Sunday's game at Soldier Field, but circumstances kept getting in the way.
Like many of you, I have never, ever understood the big-picture advantage of the zone-blitz many NFL defenses employ. There are multiple incarnations of this scheme, but in essence it swaps the role of a linebacker and a defensive lineman. If the offense runs a pass, in most scenarios the linebacker will blitz while the defensive lineman will drop into coverage.
Minnesota used a similar tactic with about three minutes remaining in the third quarter Sunday against Chicago -- with disastrous results. Vikings defensive end Jared Allen, the NFL's reigning sack champion, ended up in coverage while the Vikings rushed linebackers Chad Greenway and Napoleon Harris on a first-down play from the Bears' 49-yard line.
The Bears easily picked up the blitz; notably, rookie tailback Matt Forte stuffed Harris. Meanwhile, quarterback Kyle Orton threw a simple five-yard pass to receiver Marty Booker. Orton threw to his left and had an unobstructed view of the field thanks to Allen's drop.
Allen didn't have exclusive responsibility for covering Booker. But if you watch the replay, you see Allen overrunning Booker when he had a chance to tackle him for a short gain. Instead, Booker swiveled at the Vikings' 46-yard line and outran him to the end zone.
Vikings coach Brad Childress was questioned several times about the alignment during a Monday news conference. According to Childress, the primary strategy behind the scheme is the "element of surprise."
Yes, it's unlikely Orton would have expected to see Allen underneath the receiver, creating the potential for a turnover or at least a re-directed throw. It's also possible that an offensive line might miss one of the blitzing linebackers because it would be so focused on Allen as a pass rusher. And it's not out of the question, as Childress pointed out, that an underneath receiver would be surprised by a defensive lineman in coverage and get walloped after a short gain:
"It's kind of our kill zone, where you see defensive linemen come and run and hit people that are catching short passes or shallow crosses. The offensive guy is never even thinking of him. He's looking ahead at the guys ahead of him and defensive linemen have hits, a lot of the time, that jar the ball loose."
But the question is whether the defense is best served by having Allen rush the passer -- or hoping he surprises someone in coverage. Allen is a top athlete, but at 6-foot-6 it's not easy for him to change directions on a dime to make an open-field tackle.
The scoring play might be an extreme example, and I can't say I've seen too many instances of Allen in a role other than rushing the passer. I'm all for breaking tendencies and thinking outside of the box, but there are times when coaches out-think themselves in that endeavor. The zone-blitz might be one of those instances.