Friday, May 1, 2015

Inside the Playbook: OSU's Tunnel Screen and Slip Screen Action

I wanted to quickly go over a play design I really liked but didn’t work out due to poor execution in the Ohio State spring game. One thing I think that happens quite often in football is fans complaining about play calling. If the play call works, it was a great play call; if it doesn’t work, it was a bad play call. There is some truth to that in retrospect, but it’s rarely because of the play design or the conceptual idea behind the play. What I want to look at today is the tunnel screen and then the slip screen off the tunnel screen action.

Hit them with:

And once they cheat:

Tunnel Screen
The tunnel screen is known as a “slow screen”, this differs it from the more traditional “bubble screen” or “flare screen” which work by out flanking the defense quickly. Slow screens work because they force defenses to get into their coverage or pass rush assignments: the defenders drop into their zones and the front gets sucked in from their pass rush. Many spread teams utilize the tunnel screen as a part of their “screen option” package, where they pair a quick screen to one side of the field with a slow screen to the other. Some will refer to it as a “Jailbreak Screen” or an “Alley Screen”, and some may differentiate between them depending on the pace of the screen (for instance, an alley screen will essentially act as an inward bubble screen in that it develops quickly, while a tunnel screen will still be a slow screen).

The tunnel screen is designed to attack the natural alley that forms between the box defenders and the defensive backs. In the event of having a Cardale Jones type QB - a QB that can apparently throw a Hail Mary from his own 25 yard line – there is no depth the defense can have that is deep enough. Well the tunnel screen works by initially threatening vertically. Whether the DB is in press or playing off coverage doesn’t always give the defense an advantage. In fact, the further off he is at the snap is probably more to the CB’s benefit, as he isn’t forced to retreat or flip his hips due to the vertical stem of the WR; yet, in off coverage he becomes a bit more of a stationary target and a little easier for the blocker to identify.

Like almost any screen that attacks an edge, there are three main blocks: support, alley, and seal. In any sound defense, there is a defender responsible for forcing everything back inside (support); he needs to be kicked out to widen the field so that the receiver doesn’t have to work further back inside (if he cheats inside, you can flip your hips and seal him inside, at which point the defense is no longer sound). Any sound defense will have a defender responsible for the gap inside the support defender (we often talk about gaps between the OL – you know, A gap, B gap, C gap, but those gaps extend all the way to the sideline), this is often the alley defender that also needs to be blocked so that the play isn’t blown up immediately at the catch. Lastly, you want to seal the rest of the defense inside, and in order to do this, you need to block the next nearest threat working inside-out, at which point any other defender must work through the wash to get to the ball carrier, by which point the ball carrier can get upfield.

There are multiple ways to run this, in that you can have a RB, a playside TE, or a playside OT (with less mobile OTs, you can alternatively use your playside OG as a support blocker and use the playside OT to suck in the DE on his pass rush) act as the support blocker to a single receiver side (to a two receiver side, or a three receiver side, these players would act as the “Alley blocker”, while the second WR would act as the support blocker).

Single Receiver Side Tunnel Screen
The advantage of running this play to a single receiver side are numerous. First, it allows the receiver to work in more space. Often times with a single receiver side, you force the defense to rotate to trips or come into the box to support the run. On top of this, it helps define the coverage making life easier on the blockers because there is less movement than what you see from the space players (who will react very differently based on coverage and how quickly they diagnose the play).
Releasing a RB allows the offense to get a quicker player in space to block a space player at the support spot (typically a CB). This doesn’t allow the defense to beat the blocks with quickness. It also allows the offense to pull the defense away with a quick screen action to the opposite side of the field.

But having the RB go out to block also takes away much of the run threat, something that is often paired with slow screens. Adding play action to the tunnel screen is a great way to get the box defenders to suck inside, which in turn makes them easier to seal and expands the tunnel which the receiver is trying to hit. On top of that, if you have an OT that can move in space, you are ensured a crushing block between an OT and a CB, one in which the OT may be able to finish his block and move onto another defender.

*Sorry for the Michigan clips prior to getting to OSU in an OSU article, but Michigan ran a lot of this concept under Borges and I had the clips easily available; but the concept applies the same way to OSU and that's the point of the clips

Two Receiver Side
A two receiver side can mean a couple things: it can mean a twins set with two WRs; or it can mean a WR and TE combo. While a two-receiver side draws more attention and therefore reduces the space the ball carrier has to work in, it does have its own advantages.

First, the inside receiver can help hold the safety. One of the biggest threats to the tunnel screen is a safety working up in sky support; that allows him to work down and out, which is a difficult block for the alley blocker to get out on before the defender can blow up the play. This support can come from Cover 3, but it can also come from a Cover 4 or even Man Under coverage because that safety doesn’t have an immediate pass threat to his side, allowing him to be more aggressive downhill. In the same sense, the second receiver prevents what essentially can amount to bracket coverage on a receiver, which means both eyes are drawn to the outside receiver immediately, with one playing outside and the other defender playing inside; now the safety must respect the threat from the #2 receiver.

Second, it allows a quicker blocker to get to the edge without having to sacrifice the run threat. Now, you can still have your play action to suck in the defense, but you can get a WR or a TE to be the blocker in space to kick out the support defender.

Third, this allows the outside receiver to start the play off the LOS. In the event of press coverage, this allows him to get a free release to force the CB to turn and run with the vertical threat.
Fourth, screen action, which we’ll get to in a bit.

Multiple Receiver Side
Now we’re talking three or more receivers on a side. There are a few instances where this is applicable. First, you can now have a quicker blocker act as the alley blocker as well, which is helpful if the alley filling defender is a DB. Second, you not only can attack with the tunnel screen with the outside receiver, but also with the #2 receiver. This allows you to run off the outside CB (essentially block him by running him off) and pick on, say, a LB trying to cover a WR in space; the LB being easier to set up with the initial vertical stem.

Here, we see the TE responsible for the alley block, while the Z-WR blocks support:

Here, the outside WR runs the CB off, effectively blocking him with his route. This allows the Z-WR to run the screen.

Screen Action
You hear many coaches talk about how the screen game is an extension of their run game. This shouldn’t be true only in the fact that they are high-completion-percentage short passes that rely on the run after the catch. Like runs, they draw the defense forward. This should be used to the offenses advantage with “Screen Action”.

The traditional way to threaten screen action is to quickly get over the top of the defense with the support blocker slipping his block and getting down field (the alley defender is typically hell-bent on filling his gap, because he’s the most likely to make a play to prevent a reasonable gain for the offense). By slipping this block, he gets behind likely two DBs, the alley defender trying to fill his gap, and the support defender trying to reduce the gap to the inside of him; both DBs are essentially acting in run support here. But the thing is that the ball is still in the QB’s hands, and if the DBs have already converted to run support, that leaves a receiver wide open behind the defense.

There are two players the QB must identify here. First, the support defender. This one is easy because the QB is looking in that direction when he pumps the tunnel screen action. The second is not necessarily the alley defender (we’ll get to this in a second), but is the defender working over the top (the nearest defender going inside-out in the deep portion of the field); identify him and identify his path or angle.

To a lesser extent, screen action can work with a single receiver side. Two things make it more difficult though: selling the tunnel screen without having an illegal man downfield (this can be done by just keeping the entire OL in to block and running screen action with the receiver himself; or it can be done by flattening out the release angle of the OL to keep him right on the LOS) and then having a deep cross, likely from the inner most receiver from the far side of the field.

Something like this:

Ohio State Slip Screen
Ohio State wants it all. They want all the advantages described above wrapped up into one play, which I love from a play design standpoint. Here’s what they do:

OSU lines up with an unbalanced line, the RB aligned to strength, and a twins set to the field.
This tips things a little bit if the defense can identify it, but it tips two things that work against each other. One thing it tips is the play that will ultimately be run – the slip screen. The second thing it potentially tips is a QB sweep to the field side. Like I said, the assignments for the two plays it tips work counter to one another.

Here’s what we know.
  1. Because of the formation, there are three receivers to the field, although it looks like four receivers to the field based on the unbalanced line.
  2. We know OSU plays Cover 4 on standard downs, and we also know OSU typically uses their LBs as the alley filling defender (rather than the safety as a team like MSU does).
  3. The unbalanced line, however, keeps the OLB to the boundary inside the box, because there is no receiver to flex out over; often times, this means that he can be sealed inside to form a huge alley.
  4.  If the defense doesn’t identify that the line is unbalanced, the boundary safety is likely responsible for help over #3 to the field, meaning he is running away from the play.
  5.  If they identify the line is unbalanced, often times it will be the safety responsible for filling the alley because the OLB to the boundary is forced to play inside the box (due to the OL).
  6. The supposed “support” blocker is actually a TE, and he is eligible because of the unbalanced formation.

Here’s what happens.

At the snap of the ball, the TE releases into his “support” block. The RB replaces him to give the QB time to complete the screen action. The OLB recognizing the outside release immediately and gets on his horse to work inside-out on the WR. At the same time, the CB is trying to stick to the WR’s outside hip to make himself difficult to block (without also blocking the receiver) and reduce the alley.

1. Key #1 Down, Key #2 Drop to Center: Throw ball with velocity in seam between defenders; allow receiver to catch and run

2. Key #1 Down, Key #2 Flat: Throw ball over the top of defense. Put air on ball to let receiver adjust to throw behind defense

3. Key #1 Drops, Key #2 Drop to Center: Throw ball with velocity in seam between defenders; throw ball to inside of receiver, allow him to adjust and gain space on CB

4. Key #1 Drops, Key #2 Flat: Bracket Coverage; let play develop, if slip doesn't come open scramble or continue progression on other side.

Jones pumps the tunnel action and both the CB and OLB bite on it. But then he fails to identify his second key. He assumes the boundary safety is working over the top to the far side of the field. This means that the pass is seam, in which the trajectory is a little lower and the ball gets on the receiver a bit quicker to take advantage of the window between the underneath defenders and the safety, who will begin working from the center of the field back to the TE.

But by not identifying his second movement key, he fails to recognize the safeties angle. The safety has not committed to the center of the field and has not gained depth. This allows the safety to squat on the route and run straight down the 20 yard line and undercut the throw. What happens if Jones identifies this movement key is that he sees the safety squatting and knows that his TE can beat him over the top (the TE has a running start and has a shorter distance to travel). This ball should be lofted over the top of the safety if Jones identifies his movement key correctly.

Jones didn't identify the difference between #1 and #2 above. This is the difference between a TD and an INT. A well designed play, that gets pretty much exactly what it wanted, but not executed correctly. It’s a lot of pressure on the QB to execute it correctly, but that’s why the QB position is so difficult.

The tunnel screen is a great way to take advantage of aggressive defensive fronts because it sucks in the pass rush, and run action can be attached to it to suck in the LBs. Likewise, it puts a lot of pressure on the DBs to be sound in what is essentially run support, as they have to maintain their gaps in space. The threat of the vertical passing game forces DBs to likewise respect the deep ball, which puts them in an even worse position to defend the tunnel screen. But once the defense starts cheating on the tunnel screen, there is a natural screen action element that takes advantage of exactly how the defense wants to shut down the screen game. That's why this is such an effective play to have in the playbook, because it works in so many ways.

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