The snag concept is one of the most commonly run passing concepts in pro football today, and has been for some time.

While it has many variations (one of which we will cover more in depth in this article), the basic idea remains the same. You put three eligible receivers close together, and at the snap, one goes vertical, usually running a corner route, one breaks out and one breaks in, usually in an attempt to rub the defender who would otherwise be flying out to defend the flat.

The diagram below draws up a standard snag concept.

If the 4This is the play the 49ers actually ran in the game.9ers ran the conventional snag route from the same formation.

Contrast the diagram above with the one below, which is the play (and the defense’s response) that actually occurred.

The biggest difference between the standard example and the play that San Francisco actually ran in the game is the route (or lack thereof) by the in-breaking receiver. In both cases, the goal is the same, to disrupt the path of the defender flying out to the flat, but in this game, San Francisco tailors the route to fit the exact look they knew they’d get from Seattle.

It’s really all about the depth of the route. In the first example, the receiver #81 Anquan Boldin would run a route that sits down at five yards, assuming that the inside linebacker at that depth would be the defender you’d have to worry about stopping from flying out wide to the flat. In Seattle’s case, however, the Will linebacker aligned just outside of the left tackle is the first threat to shut down the flat route, and Boldin knows it, which is why he’s assigned to basically block that guy.

It’s also why he can get away with the physical technique he uses, because of the location of the defender.

The Play

The offense lines up with the tight end Vernon Davis lined up off the line of scrimmage.

Kaepernick doesn’t like the picture to the right side, so after making a check at the line, he’ll move Vernon Davis to the left and set up the offense to run the snag concept to the left side.

The offense sends Davis in motion from right to left.

Notice the width of the Will linebacker and how close Boldin is to him.

Boldin is lined up in a tight split and makes contact with the Will linebacker behind the line of scrimmage.

Remember that by rule, there is no such thing as pass interference when it occurs behind the line of scrimmage, so as long as Boldin doesn’t illegally hold the defender, he’s allowed to “pick” the defender by running right into him, or for lack of a better word, block him.

This leaves the fullback #49 Bruce Miller with a good amount of open space in the flat, and before Kaepernick is taken down by the defensive end, he’s able to let go of the pass and get it to Miller, who picks up seven yards and puts the offense in 2nd & 3.

A wide open fullback in the flat sets up second and three.

But let’s go back to the mechanics of how the defense reacts.

Notice that the corner aligned across from Boldin drops and opens up to take away the vertical route that he knows is coming.

The corner to Boldin’s side recognizes the “bunch” configuration being formed when Vernon Davis comes across the formation, and as a result he knows that there is going to be some kind of vertical route, likely a corner route, coming from either Boldin or Davis, so just before the snap he starts to back off and put himself in position to take away the corner route.

Meanwhile, with the corner dropping deep and the Will sealed inside, at least temporarily this opens up all kinds of space in the flat for the fullback Miller.

The Mike linebacker widens and disrupts Vernon Davis’s vertical route.

The Mike linebacker manages to disrupt the vertical route as he’s widening out to the flat, disrupting Davis’s route as he’s trying to clear the linebacker. The end result is that while the Mike is slowing up Davis, Davis does the same thing to the Mike, creating even more room for the fullback out in the flat.

Conclusion

While it’s true that successful teams get good at the basics, and master a set of base plays, the days of lining up and running the Packer Sweep and daring people to stop it are long gone. Teams need to be able to be flexible and insert answers into the game plan for specific wrinkles they’ll see from an opponent in a given week.

The 49ers give a great example of this, adjusting one of football’s most popular plays to fit their needs against one of the best defenses in football. It’s this versatile style of offense that led to so much success under previous head coach Jim Harbaugh.

Great teams never allow themselves to become prisoners of their playbook. Coaches put in a lot of stuff in training camp, but guys like former San Francisco Offensive Coordinator Greg Roman (now in Buffalo) are well-respected for their ability to craft schemes specifically suited to exploit the weaknesses of whichever opponent they’re facing that week.

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