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Jets vs. Broncos: Anatomy of a defensive bust

Denver Broncos v New York Jets Photo by Mike Stobe/Getty Images

When a defense busts an assignment, it provokes anger and outrage from fans. These guys are handsomely compensated professionals. How can they just blow an assignment?

This was a popular refrain last week as we examined the Jets’ loss to Jacksonville. On many levels, the complaints ring true. The NFL has the best football players in the world. These players have a job, and it is to execute.

Their opponents are also very talented paid quite well to execute, though. And complex plays are necessary to beat opponents of such high caliber. Complexity can lead to errors.

The Jets aren’t the only team to make these errors. Take what happened to the Broncos in the third quarter of Sunday’s game.

Defensive play calls are complicated by their very nature. A defense has no idea whether the opponent will run the ball or throw the ball before a play is run. Therefore, the defensive playcall must provide assignments for both possibilities.

On this play, to defend the run, the Broncos have seven defenders committed to stopping the run. They are each assigned one of the seven gaps in the Jets’ formation. A gap is the space between blockers up front.

Against the pass, the Broncos are playing man to man coverage. The most notable pass assignment is number 29 Bradley Roby matched up against Quincy Enunwa.

Enunwa is sent in motion, and this starts a chain of events that leads to disaster for Denver. Roby follows him.

Darian Stewart (number 26) makes a signal with his hand telling Roby to stop following Enunwa. It is difficult to follow a receiver in motion across the formation. As you can see above, Roby is behind Enunwa. The Jets could snap it quickly, and Roby would be out of position.

Stewart is essentially saying to Roby, “Stay where you are. We are switching assignments. I will now have Enunwa in man coverage.”

Taking Enunwa means that Stewart will no longer be able to help against the run. To compensate for this, two linebackers shift over. Brandon Marshall slides over to take Stewart’s old gap, while Josey Jewell slides over to take Marshall’s old gap. (Old gaps are in pink; new gaps are in yellow.)

You can see the new gap assignments here. (Marshall’s and Jewell’s changed assignments are in yellow.)

You might notice a problem here. The gap between Kelvin Beachum and Eric Tomlinson is unoccupied. Roby did not get the message and continued to follow Enunwa. That was Jewell’s old gap. When Jewell slid over, Roby was supposed to take it.

Here’s what the assignment looks like with a lifelike illustration of Roby filling that gap.

Stewart was supposed to take over for Roby covering Enunwa man to man. Marshall was supposed to slide to take Stewart’s gap against the run. Jewell was supposed to slide to take Marshall’s gap against the run. Roby was supposed to release Enunwa and take Jewell’s gap against the run.

Everybody got the message except Roby, which left a gap undefended.

The Jets were quite happy to run the ball into this undefended area.

Isaiah Crowell ripped off a 54 yard gain.

It is easy for fans to forget there are two teams on the field. A week ago, Jets fans were understandably upset with their defense for all of the blown defensive assignments. Part of the story, however, was that the Jaguars deserved credit for making the Jets pay. Just because the defense messes up doesn’t mean the offense will automatically create a big play. On the same note, the Jets deserve credit here for making Denver pay for a mistake. The Broncos bust this play, but the Jets also block up front very well, and Crowell runs with speed and authority to prevent Denver from covering for its error.

In here there is also a lesson about why teams use presnap motion. It frequently forces the defense to adjust its assignments quickly before the snap. That requires quick and effective communication in a high stress setting. It only takes one person to miss the message for disaster to strike.

(The motion has another impact. Had the Broncos executed better, the Jets still would have created more favorable matchups against Denver’s defense. If the Jets threw, a safety would be one on one against Enunwa. Against the run, a corner would have to defend rather than a safety.)

You might now understand why offenses like Kansas City utilize so many complex presnap motions. The more the defense has to adjust, the greater the odds of a bust.