The Deep Post: Breaking Down the San Francisco 49ers' Texas Stunt

Matt Miller@nfldraftscoutNFL Draft Lead WriterSeptember 5, 2013

SAN FRANCISCO, CA - JANUARY 12:  Defensive end Justin Smith #94 of the San Francisco 49ers in action against the Green Bay Packers offensive line during the NFC Divisional Playoff Game at Candlestick Park on January 12, 2013 in San Francisco, California.  (Photo by Stephen Dunn/Getty Images)
Stephen Dunn/Getty Images

Much has been written in the last six months about how the Green Bay Packers must stop the San Francisco 49ers read-option offense. But how do the 49ers stop the vaunted Green Bay passing game? 

As the old SportsCenter highlight goes, you can't really stop Aaron Rodgers, you can only hope to contain him. That's what head coach Jim Harbaugh and defensive coordinator Vic Fangio have been toying with since the regular-season schedule was released—how do we slow down Rodgers and the Packer passing game?

To know how to stop the Green Bay offense, you must first understand it. Casual fans know that head coach Mike McCarthy loves to throw the football, and that Rodgers has a ton of weapons to throw to at wide receiver. That's a good foundation, but how does this offense work? 

McCarthy, who came to Green Bay via San Francisco, has built an offense based on old-school West Coast offense concepts. He's added in wrinkles like the shotgun formation and more one-back sets, but the route concepts are classic Bill Walsh. That means flooding one side of the field and giving the quarterback an easy read so that he can get the ball out quickly.

The West Coast offense was built for quarterbacks, and the Packers' staple passing play—a dig/seam route combination—is a great example of this.

Rodgers, in the shotgun, has 11 personnel on the field—that's one running back and one tight end. In this formation, the tight end, Jermichael Finley, is not lined up on the end of the offensive line, but in a flex position one yard off the ball and detached from the right tackle. With one wide receiver split left and two to his right, Rodgers has an overloaded formation on the right. 

When the ball is snapped, the route combination begins. 

Tight end Finley releases with outside technique to get away from the outside linebacker. Outside wide receivers use inside technique to gain positioning on their routes. The slot receiver runs a basic seam route while the outside receiver (the "Y") runs a dig route.

Rodgers will be looking from the seam, to the dig, to the out route run by Finley. If all are covered, he can go to his backside to check the go route being run by the "X" receiver. If all else fails, the back is releasing into the flats after checking for blitz protection.

This play is a Cover 2 buster, but it works well against any zone defense because the routes can all be broken off if the receiver recognizes space. Now that we know what to expect from Green Bay, how will San Francisco defend it?

When Harbaugh and Fangio took over the 49ers they changed many things, but perhaps the best thing they did was to bring the Texas Stunt with them from Stanford. With defensive end Justin Smith already in place and outside linebacker Aldon Smith coming via the first pick of the Harbaugh-era, the team had the horses in place to run this nearly unstoppable play.

The Texas Stunt works much like the read-option does—causing confusion and taking advantage of a mistake. The defensive end and outside linebacker read the offensive linemen, attacking where they sense a weakness. 

When the ball is snapped, defensive end Justin Smith takes a hard step toward the outside shoulder of the left tackle. His goal is to get to the tackle to take a big kick-step to the outside, as this opens up a pass-rushing lane on the inside—or "B" gap—for Aldon Smith. Justin Smith takes away the outside and Aldon Smith loops around, attacking the "B" gap and an offensive guard that is ill-suited to take on his athleticism.

This play works because the 49ers have two ridiculously talented pass-rushers on the right side of the defense. Against All-Pro tackles this play produces well, but against a fourth-round rookie like David Bahktiari, it will be money. 

Bahktiari, making his first NFL start, must resist the urge to go outside to stop Justin Smith, but therein lies the problem. If Justin Smith is left free to crash the edge, he's quick enough to get to the quarterback as an outside pass-rusher.

If Bahktiari leaves the "B" gap and takes his kick-step to get Justin Smith, he's left a massive hole for left guard Josh Sitton—who is one of the best in the game, mind you—to cover. Sitton may be a top-tier guard, but that's a huge gap to fill.

From a purely physical standpoint, asking a guard to slide laterally and meet a hard-charging linebacker coming at full-speed isn't fair. Sitton must slide and get his feet set before Aldon Smith gets to the gap, otherwise he'll be on the receiving end of a 260-pound bull rush.

The Packers won't see a Texas Stunt on every play, but this is a third-down staple for the 49ers defense. In the NFC playoff game last year the 49ers went to the Texas Stunt any time they were in a nickel or dime personnel, and it worked. According to Pro Football Focus (subscription required), Rodgers was hurried 17 times in the game. 

If the 49ers can generate that pass rush and pressure against veteran offensive linemen, imagine what they'll do against a rookie? 

The key for Green Bay is to get the ball out quickly, something Rodgers has not always been great at. Behind a patchwork offensive line, he'll need to be at his best. A healthy Smith Bros. attack is the biggest concern for the Packers offense, though, so expect much attention to be paid to the right side of the 49ers defense. 

As this is a play regularly seen on third down or in obvious passing situations, the Packers may have to lean on the running game more than normal. With the 49ers in a defensive formation that features just two down defensive linemen, the field is open for the run if you can get past the three All-Pro linebackers on the roster. 

What makes this defense so tough to beat is that each player holds their assignment so well. Fangio is able to use two down defensive linemen because he trusts that Patrick Willis and NaVorro Bowman will make tackles in space if runners get through the defensive line. And it helps that those linemen—Smith and Ray McDonald—both excel at getting pressure and making tackles on their own.

The back end of the 49ers defense may be the sweet spot for Green Bay. If Rodgers can find time to get the ball out, his wide receivers are a good matchup against Carlos Rogers, Tarell Brown and Nnamdi Asomugha. But as every player who has ever lined up in the secondary knows, a great pass rush will hide a lot of flaws in coverage.

Who will come out on top Sunday afternoon? It will be the team that wins when the Texas Stunt is unveiled.