The drift concept is one of the most widespread concepts in the NFL and is the most used play-action concept of 49ers‘ head coach Kyle Shanahan.
The play is called drift as it revolves around what Shanahan calls a drift route. A drift route is a six-step speed cut in route when run from a tight split, and seven steps when ran from a wide split. It predominantly runs from a tight split.
Almost every example I’ve seen drift been called it’s been against single-high coverages, either Cover 1 (man) or Cover 3 (zone). Due to the 49ers’ dominant run game, they face single-high coverages very frequently on early downs. Drift is a way to take advantage of defenses that are trying hard to slow down the run game.
When facing a receiver with a tight split, the cornerback in Cover 3 will almost always play about 7 yards off the line of scrimmage (LOS) and have heavy outside leverage. Attacking the leverage of the defender is almost always a good idea for a receiver, which is why the receiver uses a widen release when running a drift route from a tight split.
The reason why the cornerback plays with outside leverage in Cover 3 is because he has help inside from the safety in the middle of the field (free safety) and the linebackers. As the play above illustrates, the cornerback has little chance of defending the drift route himself, thus forcing either the linebackers or the FS to defend it.
This is why the most critical aspect of the play is the linebackers, or more specifically, the linebacker who is aligned in the window for the drift route.
The illustration above is a rough estimate of the drops the linebackers (second level defenders) will take. As it shows, the only defender that will likely be in the window is #53, who is the mike linebacker on this play. It’s usually the case that the mike LB is the one in the window when ran from a tight split.
If it was a dropback pass (no play fake), the Mike would comfortably drop back into the window, which is why the play-action is necessary as the offense needs him to flow aggressively towards the LOS. This is why the 49ers’ use of drift varies a lot from week to week as Shanahan pre-dominantly uses it as a way to target aggressive mike LB’s.
On this play, the 49ers’ Mike doesn’t flow downhill at all, making it easy for him to sink back into the window.
This play is the complete opposite as Joe Schobert buys the run fake, opening up tons of space in the window for the drift.
However, if the Mike (or whoever is the LB in the window) flows downhill but not past the point of no return, it’s the quarterback’s responsibility to beat him, either with his eyes or with the throw.
After reading pass, the underneath defenders will read the quarterback’s eyes in order to determine where to sink back to. The quarterback doesn’t need to be as overt as something like the following from Mahomes, but a quick look away from the drift window is critical.
Notice how Watson’s subtle look away from the drift route opens it up.
Another responsibility the quarterback has on the play when it comes to deceiving the Mike LB, is with selling the play fake.
A way to counteract linebackers that are sinking back quickly after seeing the quarterback keep the ball is throw a screen.
The second most important aspect of the play is containing the free safety. This is mostly a game-plan thing as a free safety’s alignment and aggressiveness will usually stay consistent week to week.
On the following play, the Texans are apparently playing Tampa 2 invert, which is the same as Tampa 2 (Cover 2 with the Mike dropping to the deep MOF), but with the CB's as the deep half defenders and the FS playing the mike’s role. So, this is as aggressive you will see a FS play as he has help over the top. This coverage predictably shuts drift down.
Here’s another play where the FS stays flat-footed and drives aggressively on the drift route.
These plays are certainly in the minority as when the FS is responsible for the middle of the field (Cover 1 or Cover 3), he will usually back-pedal and be slow to drive down on routes underneath him as his primary responsibility is ensuring no receiver wins in the deep middle of the field.
A way to get the FS to play more conservatively is to call a play that attacks the deep MOF, which is also a good way to take advantage of an aggressive FS. A concept in Shanahan’s playbook that will look similar to drift to a FS is heat.
Shanahan called heat later on in the game and notice how much more conservatively Harrison Smith is playing after having someone beat him over the top.
Another way to attack an aggressive FS is to use an outside run play fake (the play fake on drift is predominantly an inside run) away from the drift route and have the receiver align out wide. Due to his wider split, he will have a more difficult time beating the cornerback but it still shouldn’t be much of a challenge. If the FS is aggressive he will likely only be able to make the tackle at best.
Drift is nowhere near as effective against Cover 1 (or any type of man) as the defender will play the route much tighter.
However, it can still be a good play if the matchup is good as the defender will still be leveraged outside when the WR has a tight split as he again has help inside.
The receiver that predominantly runs the drift route for the 49ers is Kendrick Bourne.
I would change two things to improve how the 49ers run drift: have the WR stem his route further outside when from a tight split, and have Garoppolo look away from the drift route after the play fake. In order for Garoppolo to be able to look away from the drift route, the play fake would have to be away from the drift route, which is currently only the case about half the time. This would also be an improvement as the defense will be flowing away, and not towards the drift route. The timing will stay the same as even though Garoppolo will be slightly later, the WR will also be slightly later.
This will give the FS more time to react but will move the Mike more, and as mentioned above, the mike is more important than the FS.
Here’s a look at the WR stemming his route wider than the 49ers do:
In summary, the key to the play is for the defense to have an aggressive Mike LB and a conservative FS.