Why do offenses send players in motion before the snap?
Over the course of 2021 Summer School series we’ve been looking at how offensive coordinators can use elements of their play to give their players an advantage before the ball is snapped.
We started by looking at the strengths and weaknesses of the most popular personnel groupings in the NFL, and followed that up by going over how offenses can manipulate defenses with their spacing. Last time we saw how, and why, offenses script their opening drive (or drives) to gather information about the defense.
This time we’re going to take a look at how offenses can use pre-snap motion to actively gain information on defenses, as well as manipulate them at the start of the play.
What is pre-snap motion?
The next area of information gathering we’re going to look at takes place just before (or during) the snap. That’s the use of pre-snap motion in the offensive play. Pre-snap motion has become widely used at the collegiate level, and increasingly common at the NFL level. We can see a broad range usage from NFL teams, ranging from the Baltimore Ravens sending a player in motion on 36.6 percent of plays all the way to the Tampa Bay Buccaneers using motion on just 2.9 percent of plays (through November 19th).
— Seth Walder (@SethWalder) November 19, 2020
The fact that there are very good offenses at opposite ends of the spectrum shows that motion is anything but a necessity. However, it’s also true that motion seems to have a positive impact on offenses.
Per ESPN’s motion tracking, eight of the 10 teams that most frequently use motion were also in the top 14 of Football Outsiders’ DVOA rankings.
Pre-snap motion in action
Sending a skill position player in motion before the snap can do several things for the offense.
The first, and most commonly cited, advantage of pre-snap motion is to force the defense to declare itself and give the quarterback some context clues as to what coverage scheme it is playing.
Here we see the Green Bay Packers line up in a 21 personnel package with a condensed formation, forcing the defense to bunch up at the second level. The Packers send their second running back, Tyler Ervin, in motion from the left side of the formation to the right side.
We can guess based on the defense’s alignment that they’re likely in a Cover 4 defense. When the player goes in motion we see that the defense barely moves, that confirms the initial suspicions of a Cover 4 shell. With that knowledge, Rodgers knows where to put the ball and how to attack this defense.
The Packers run what looks like a modified Mills concept, using play action which transitions into a wheel route. The play action and pre-snap motion holds most of the defense and pulls it slightly to the offensive right. That forces the void between the corner and safety on the offensive left to expand. That creates a nice hole for Rodgers to find the X receiver for the big gain down the field.
But that’s not the only use of pre-snap motion.
One of the less-obvious advantages of pre-snap motion is misdirection, which can help move defenders out of position. This is particularly effective in the running game, when the offense needs the play to hit quickly and gain as much of a numbers advantage as possible.
Here we see the Ravens send a player in jet motion just before the snap, running from the right side of the formation to the left.
This is a relatively simple run between the tackles, but the defense is forced to account for the jet motion. We can see the second level defenders shift as the player begins his motion, respecting the possibility of a jet sweep. That shift pulls the defenders on the play side out of position to effectively fill their gaps, creating a void in the defense and an opportunity for blockers to get to the second level.
The quick-hitting play is able to get the runner in space before the defense is really able to react. And despite the Eagles starting the play with eight defenders around the line of scrimmage and tackle box, the Ravens’ play design (and execution) allow them to pick up 9 yards up the middle.
When the game of football is played at its highest levels, both in the college ranks and especially at the NFL level, the devil really can be in the details. And things as seemingly small as having a receiver run across the formation really can be the difference between the success or failure of a play.
Pre-snap motion can clue offensive coaches into how the opposing defense is going to respond to certain looks. It can give the quarterback insight into how the defense is disguising its intentions. Pre-snap motion can help the offense by creating an unexpected numbers advantage on one side of the field, or even by simply slowing down the defense by giving them one more set of possibilities to process and track.
This year we’ve been concentrating on the little things on the offensive side of the ball, the devilish little details that show up in every single highlight reel play, but are only rarely mentioned. Things like player selection, formation construction, and information gathering can all be vital tools for stringing together successful plays and coming away with the win.