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Film Study: Analysis of The Empty Set in The 2009 Big Game (Part I)

This is the first post in a two part series examining the "chess match" between Cal's offensive coordinator Andy Ludwig, and Stanford's defensive coordinator Ron Lynn.

Back when I ran my Post-112th Big Game Thoughts post, I noted how Ludwig was using a simple tactic in the passing game to get player mis-matches:

Cal was also using a little neat trick with the empty sets to get player mis-matches.  Specifically, Ludwig would put the TE and RB out as the widest receivers leaving the slot receivers (the WRs) inside and lined up against safeties and linebackers.  This is a very simple tactic to get mismatches.  I will cover this in-depth in a frame by frame analysis later on.

Seeing this tactic during the game made me ponder if the defense would adjust.  It wasn't until I got the game film (and had more time on my hands) to rewatch the game that I noticed the very interesting chess match going on between Cal's offensive coordinator Andy Ludwig, and Stanfurd's defensive coordinator Ron Lynn.

(Long and intense football analysis with pictures to come after the jump...)

Before I get into the analysis, I suppose a brief explanation of the empty set is prudent.  The empty set is a formation where the offense lines up with five receivers and nobody in the backfield other than the quarterback (hence the name "empty").  I specifically used the word "receivers" and not "wide receivers" because not all teams use wide receivers in their empty sets.  Instead, some teams also use tight ends (TEs) or runningbacks (RBs).  Thus, the key defining factor of the empty set is really that there are five receivers, not really that there are five wide receivers.  Regardless of whether the offense uses WRs, TEs, or RBs, those players are all usually pretty fast and competent pass catchers.

Cal is one of those teams that has consistently used TEs and RBs in its empty sets instead of putting five WRs on the field.  Cal has also always put their QB in shotgun when in the empty formation.  Some teams don't put their QB in shotgun and instead the QB will take a drop from under center.  I believe Cal likes to put its QB under center because Cal always passes out of the empty set and thus this provides the QB with more time to read the defense, set himself, and throw, rather than also having to worry about his dropback. 

The purpose of the empty set is to spread out the defense - a lot.  Receivers will be spread from sideline to sideline forcing the defense to cover the wide side of the fields too.  Also, the defense will usually also have to substitute out slower players for faster players.  As since most teams don't have tons of talented fast players - usually secondary players like cornerbacks and safeties, the empty set really strains defenses that don't have talented depth.  Thus, the defense is essentially presented with the option of: (i) subbing in faster players that match up better against the offensive's speed receivers but whom aren't as talented as the normal starters, or (ii) to leave in the normal  starters, such as linebackers, who may be better players overall but just aren't that fast.

Cal used the empty set formation six times during the 2009 Big Game.  I will analyze the first four plays below in this post, and the final two plays in my second post.  (Please excuse my crappy Microsoft Paint pictures as since I no longer have Photoshop on my computer).




The first time Ludwig called up the empty set formation, was in the first quarter on a 1st and 10 (see picture above).  As you can see, Cal has five receivers on the field. 


It's hard to see which players are actually on the field, but I believe that Cal has put the TE to the offense's far left, and the RB (Vereen) to the offense's far right (see picture above).  The other three receivers in the slots are WRs (Lagemann, Jones, and Ross).  This is the neat little trick that I talked about in my post-game thoughts.  Ludwig is trying to get a mis-match on the defense by putting WRs in the slot.


The Stanfurd defense plays their 4-3 defense in response.  Do you see the mismatch here?


Most teams, when playing man defense, will have their cornerbacks cover the outer-most receiver.  Thus, hypothetically assuming that Stanfurd is playing a man defense, the coverage would be as shown above.  Note that the cornerbacks (CBs) - the defense's best pass defenders, are on the outside covering the offense's RB and TE who are the offense's worst pass receiving threats.  Also note that the linebackers (LBs) - the defense's worst pass defenders (excluding defensive linemen) are on the inside covering the offense's WRs who are the offense's best pass receiving threat.  This is the mismatch!  Ludwig is hoping to exploit the defense by putting his best receiving threats - the WRs, in the slots, matched up against the defense's linebackers who are usually slower than the WRs and poor pass defenders!

Let's see how the play turns out.


Here's the post-snap picture.  Stanfurd rushes the QB with their four defensive linemen.  The other seven defenders drop back into coverage. 


It's hard to see the routes of the other WRs, but Lagemann, the only WR visible in the picture above runs an "in" route after giving a slight stutter step fake to the outside.  Also, Ross, the WR in the left inside slot, runs an out route. 


Riley doesn't seen anybody open and begins scrambling to his right for a modest gain.

So what did Ludwig, as an offensive coordinator learn from this play?  Let's take a look. 


Here's the offensive playcall.  As I stated earlier, the inner slot WRs run and "in" and and "out."  The other three WRs run "go/streak/fly" routes (different names for all the same thing).  What Ludwig is looking to see, is how the defense responds.  So how does the defense respond?


As I stated earlier, Stanfurd chose to defend against Cal's "11 personnel" (3 WRs, 1 TE, 1 RB), with their 4-3 defense, meaning that they put four defensive linemen on the field, three linebackers, and four defensive backs.  But what was the defensive coverage?  Stanfurd put their defenders in a Cover 4 defense - which is also commonly known as "quarters."  This is a defense which puts four deep defenders across the field each of whom are responsible for 1/4th of the deep field.  I've shown the quarters coverage in the picture above with red boxes.  Underneath the quarters coverage, it appears as if Stanfurd has their linebackers in zone coverage which I've shown with red ovals. 

Now that Ludwig knows the defense that Stanfurd will likely use to counter the empty set during the remainder of the game, Ludwig can plan to exploit the defense from this formation.  So what are the vulnerabilities of the quarters coverage? 


Well, one of the simplest weaknesses of the quarters defense is that it has a void in the short outside zones.  I've shown that area in the picture above with the green circles.  Ludwig is keeping this in mind for when he uses the empty set again later on.

Here's the video for the play (special thanks to ieeebear for making these videos for me):


Quick recap:
*Cal in empty set formation.
*Cal puts WRs in slots, and the TE and RB outside.
*Stanfurd rushes four.
*Stanfurd plays quarters coverage with linebackers in zone.
*In a chess analogy: Ludwig has moved his pawn to see how Lynn will react.




The second time that Cal used the empty set was only two players later on a 1st and 10.  Is Stanfurd going to defend the empty set with the same defense?  It looks like it.  Stanfurd again comes out with its 4-3 defense and appears to be showing quarters coverage again although this time the CBs are showing press coverage.


Is Ludwig going to attack the short outside zones of the quarters coverage?  It actually appears as if Ludwig has something else in mind.  Ludwig has put WRs on the outside, and put RBs on the inside slots.  Vereen is the right RB, and Sofele is the left RB.  What is Ludwig up to?


Ludwig calls up a play featuring the appearance of double bubble screens.  Both of Cal's RBs run swings as if to catch the screen pass.


The Stanfurd LBs see the RBs' lateral movement (shown above with the yellow lines), and react aggressively.


But this play is really a fake bubble screen play!  Tucker slips behind the Stanfurd linebacker.  Note the huge window that Riley has to throw through (the big lime colored triangle).  This huge window formed because the other two Furd LBs bite hard on the fake bubble screen to the offense's left. 


Tucker catches the ball for a huge gain! 

So why did Ludwig decide to go with this fake double bubble screen?  Well, after the first play, he knew that there was a good chance Stanfurd would defend the empty set with the quarters coverage and zones underneath again.  If they did, then Ludwig was hoping to take advantage of the LBs' tendencies to react quickly and aggressively to plays in front of them.  Stanfurd did play the quarters coverage against with zones underneath, and the LBs were victimized just as Ludwig had planned.  Another reason is that this play essentially acts like an option play targeting the linebacker.  The linebacker is presented with two offensive players to defend.  First, the runningback.  Second, the WR.  The LB doesn't really know that the WR is running a route so he'll usually bite on the RB route, thus leaving the WR open.  Because the defense is playing a Cover 4, the secondary defenders are too far away to stop the pass to the WR.  If by chance the LB didn't bite on the RB route and instead (and unknowingly) covered the WR, then the QB would pass the ball to the RB.  Either way, clearly, Ludwig is focusing on the Stanfurd LBs out of the empty set.

Here's the video of Play #2 (special thanks to ieeebear):


Quick recap:
*Cal in empty formation
*Cal puts WRs outside, and in middle slot.  Puts RBs in inner slots.
*Stanfurd rushes four.
*Stanfurd plays quarters coverage with zones underneath.
*In a chess analogy: Ludwig has just forked Lynn's bishop and rook with Ludwig's knight.




Here's the presnap picture of when Cal used the empty set for the third time.  This occurred in the second quarter with about 6:35 on the clock.  Cal is facing a 1st and 10 in their own territory.  It's hard to tell the personnel that Cal has on the field, but I believe it's all WRs, thus five WRs are on the field.


Here's the post-snap picture.  Note that Stanfurd again rushed four pass rushers, specifically their four defensive linemen.


Again, it appears like Stanfurd is defending this empty set with their quarters defense with linebackers in zone underneath the quarters coverage.


Here we see both of the inner-slot WRs (Lagemann and Ross) break to the outside... towards the hole in the quarters coverage (shown with blue arrows above)!  Stanfurd has no chance to defend the play as since their LBs are attempting to cover faster players. 


I've shown the open void in the quarters coverage that Ludwig is attacking (see the green circle above).  Note the outside WR at the bottom of the picture (the offense's very left-most WR), helps create this void by "running off" the Stanfurd CB who is playing quarters coverage to that 1/4th of the field. 


Here's a better view of Lagemann catching the ball in the void of the quarters coverage.  The void is the green circle.  The blue arrow represents the route of the Cal WR that "ran off" the quarters coverage defender to that side of the field.  You can see barely see the deep quarters coverage to the left side of the picture which I've represented that with red boxes.  You can also see the Stanfurd LB zone which I've represented with a red oval.

I'm sure Ludwig had this play in mind and was just saving it for when he really needed it.  He knew it work.  He knew there wasn't really an issue of the play not succeeding so long as the offensive line gave Riley enough time to pass and Stanfurd defended the empty set with the same quarters coverage zone underneath that they had been the previous two times.  As since the defense responded just as Ludwig predicted they would, I'm sure Ludwig was thinking he had an easy-gain play that he could use over and over again until the defense adjusted.  So the question now becomes: how often do you keep using this play since you know it will work and the defense hasn't shown any adjustments? 

Here's the video of Play #3 (special thanks to ieeebear for making this video):


Quick recap:
*Cal in empty set. 
*Cal uses 5 WRs
*Stanfurd rushes four.
*Stanfurd plays quarters coverage with linebackers in zone.
*In a chess analogy: Ludwig has Lynn in check.




In the last play I left off with the question: how often do you keep using this play since you know it will work and the defense hasn't shown any adjustments? Well, the answer is: only about nine plays later in the same drive.  Yup, nine plays later, Ludwig calls up the very same play again!  Let's just call it "the money play."


Here's the post-snap picture.  Note that Stanfurd has, again, rushed four pass rushers, specifically their four defensive linemen.  They also have chosen to defend the empty set again with their quarters coverage and linebackers in zone underneath. Note that the outer left receiver(the receiver at the bottom of the screen) runs off the quarters defender again.  The outer right receiver does the same, as does the middle slot receiver to the right. 


And just like the last play, the inner slot WRs run their out routes (Ross runs his out route deeper than Lagemann - perhaps by design).  Again, Ludwig is targeting that short outer zone of the quarters defense by using mismatches on the Stanfurd LBs. 


Riley completes the pass to Lagemann who gets another reliable eight yard gain!

By this time, unless the defensive coordinator is an idiot, he must have noticed what Ludwig is doing.  Changes must be made lest he want to lose the game.  At this point, Ludwig has also got to be pondering whether he should try and push his luck and call the same play again!  Ludwig has called the empty set formation four times thus far.  Stanfurd has defended the formation with the same defense all four times.  Ludwig has exploited the defense three out of the four times.  I guarantee that Ludwig was wondering whether he had the cajones to push his luck and call this play again before halftime.  However, Cal scored a touchdown four plays later and thus Ludwig did not have another opportunity before halftime to push his luck.

Here's the video of Play #4 (special thanks to ieeebear for making this video):


Quick recap:
*Cal in empty set. 
*Stanfurd rushes four.
*Stanfurd plays quarters coverage with linebackers in zone.
*In a chess analogy: Ludwig has Lynn in check... again.


Intermission Summary:

It is now halftime.  Cal's offensive coordinator Andy Ludwig has called the empty formation four times in the first half. 

The first empty formation playcall featured Lagemann on an "in" route over the short-middle of the field.  This is Ludwig's staple play that he runs out of the empty formation (see the 8th picture from the top).  While this play is being executed by the offense, Ludwig is watching the defense to see how they will respond to this play.  Stanfurd defended the empty set formation with quarters coverage and zones underneath (the quarters coverage).  Stanfurd only rushed four pass rushers; their four defensive linemen.  Now Ludwig knows how Stanfurd will defend the empty set in the future (although it's still possible that Stanfurd's defensive coordinator Ron Lynn might try a different defense if presented with the empty set formation again, so Ludwig can't quite assume with 100% certainty that he'll see quarters coverage again but Ludwig knows that quarters coverage is a strong possibility).

Assuming that Stanfurd would play the same defense against the empty formation, on the second play Ludwig called the double bubbles play (Play #2) to attack the Stanfurd LBs in zone.  As the play was executed, it was revealed that indeed Stanfurd was again playing the same defense: quarters coverage with zones underneath and a four man rush.  Now that the defense has defended the same offensive formation with the same defense both times, Ludwig knows all he has to do is call up plays out of the same formation that attack the weaknesses of the quarters coverage.

Ludwig does exactly that on the third and fourth plays.  On those playcalls, he modifies the routes so that both slot WRs break outwards to the sidelines, rather than sending Lagemann on an "in" over the middle because the weakness of the quarters coverage is to the short outside areas of the field (the area just deeper of the "flats" area).  Both of these playcalls worked to perfection and resulted in completed passes for easy gains.

Ludwig knows that he has a "money play" in his pocket right now.  He's wondering if he'll be able to use the same play throughout the rest of the game, or if the Stanfurd's defensive coordinator Ron Lynn will adjust to take away the "money play."  What will happen in the second half of the game?  Find out in Part Two of this film study analysis!