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The DC Times

A New Way to Look at the Cowboys, NFL, and Fantasy Football

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Re-Analysis of 4th Down Attempts: The Impact of Momentum

Optimal 4th Down Decisions via mgoblog.com

A couple days ago, we published a study on the Cowboys’ 2009 4th down attempts, explaining why the offense, along with most others around the NFL, does no attempt nearly enough 4th down plays.  The Cowboys attempted just 11 plays on 4th down last season, converting on only four of them (36.4%).

Last night, I came across another study on 4th down attempts.  The conclusions of their original study were similar to those we discussed in our own article.

  1. Don’t punt on the opponent’s side of the field.
  2. Really consider going for it on 4th down after crossing your own 40.
  3. Field goals only make sense if there are more than 5 yards to go and you are between the 10 and 30 yard lines. If you’re in opponent territory and these two criteria aren’t true, you should be going for it.

However, they also raise (and rebut) a couple of objections to the “go for it” dictum.  They are listed below.

  • Failing on a 4th down attempt gives the opposing offense momentum they would have otherwise never received.

Offenses have no advantage if their drive is the result of a 4th down stop.

This was initially our biggest qualm with the notion of adhering to a (seemingly risky) 4th down chart.  The methodology seemed like it may work in principle but be less representative of reality when human emotions came into play.

However, the graph to the left shows that 4th down stops actually do not generate momentum for opposing offenses.  In fact, from 2007-2009, the total points obtained by drives following 4th down stops (2523) is less than the projected points for any drives starting at the same field position (2580).  Thus, “the big mo” appears to be more like “the big no,” at least as it relates to 4th down stops.

  • The model does not account for game-specific situations.

This is actually a valid objection.  MGoBlog.com points that out, writing:

The main flaw with the expected points model is that for most of the game all points are largely equal but at the end of the game, a field goal or even time can become crucially important.  If a field goal can tie a game, take the lead, or move said lead from one possession to two (or vice-versa), the decision-making process suggested above can shift radically.  This could mean punting near midfield to prevent a short field goal drive for the other team or taking a field goal instead going for it on fourth in field goal range.

However, the effect of situational 4th down calls is not as great as you may assume.  Until the 4th quarter, a coach’s decisions cannot be strongly correlated with the outcome of the game.

For example, when a team is down by four points with 30 seconds to go, the decision to go for it on 4th down is easy.  In the 3rd quarter, however, there are enough possessions left that there is less predictive power regarding the coach’s decision and the final score.  Thus, the 4th down chart is at least viable into the 4th quarter, and probably a bit beyond.

In any event, offenses around the league could benefit vastly from a more aggressive approach to 4th down play-calling.  Failures to convert appear to have little impact on game momentum, squashing our biggest fear of the real-life application of the model. Further, game-specific decisions are not nearly as common as people may believe.

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Cowboys Film Study: 2nd and 1 Play-Calling

Advanced NFL Stats has published two interesting articles on the value of 2nd and 1 plays and the poor play-calling displayed throughout the NFL in these situations.  As you can see in the graph below, a nine yard gain on 1st down is extremely valuable to an offense.

Courtesy of Advanced NFL Stats

Why?  Well, think of it from the perspective of a defensive coordinator.  You want to stop the run to prevent a 1st down, but playing too aggressively against the run would create a vulnerability in your defense should the offense decide to pass.  Since 2nd and 1 is such a tremendous risk/reward situation for an offense, they could very well take a shot down the field.  If the result is an incomplete pass, they have a rather easy (relatively speaking) 3rd down play (meaning low risk), but the upside of a deep playaction pass, for example, is outstanding.

Game theory dictates that NFL offenses should be in the business of maximizing upside and minimizing risk, while defenses are looking to create low reward/high risk situations for offenses.

The value of a 2nd and 1 play is so incredible that, on average, a team will score .7 extra points each time they gain nine yards on 1st down as compared to gaining 10 yards.  Yes, gaining one less yard on 1st down provides a team with .7 more “expected points.”  In fact, 2nd and 1 plays are so valuable that they yield more expected points than any 1st down gain all the way up until 17 yards.  Thus, a nine-yard gain on 1st down is actually more valuable to an offense than a 16-yard gain.

The value of 2nd and 1 plays is even greater, though, if offensive coordinators take advantage of the situation.  This is not the case, however. League-wide, coaches called a run play on 78% of all 2nd and 1 plays.  That is even more than the 76% rate on 3rd and 1’s!

Further, only 4% of 2nd and 1 plays result in the offense going deep (throwing 15+ yards in the air).  This is fewer than all other 2nd down situations except 2nd and 4.

So why aren’t coaches taking advantage of the outstanding opportunity that comes with 2nd and 1 plays?  Disregarding the fact that most NFL coordinators are simply naturally conservative in their play-calling, we think the main reason is that they don’t want to deal with the stress of 3rd down.

Instead of utilizing the potential upside of 2nd and 1, they treat it as if it was simply another 3rd down.  Two opportunities to run the ball for just one yard?  Sounds good to me.  This thinking initially appears rational because it is the combination of plays which is most likely to result in a 1st down.  Offensive coordinators are supposed to do everything possible to obtain 1st downs, right?

Well, yes and no.  Of course a team needs to acquire 1st downs to move the ball, but coordinators should not be so focused on getting that next 1st down that they miss an opportunity for a huge play.  Take a look at this example:

Team A has 50 2nd and 1 situations throughout a season, running the ball on nearly every one.  They obtain 45 1st downs, but zero touchdowns on these plays.

Team B also has 50 plays on 2nd and 1, but they take a more balanced approach.  They throw about half the time, resulting in just 35 1st downs.  However, they score a touchdown on six of these plays.

So, which team would you rather coach?  For us, the low risk/high reward results obtained by Team B are much more appealing (and much more strongly-correlated with winning) than those of Team A.

Thus, offensive coordinators could increase the expected points of their offense dramatically by throwing out conventional wisdom and opening up the playbook a bit on 2nd and 1.

As you can see in the graph to the right, Cowboys’ offensive coordinator Jason Garrett’s play-calling on 2nd and 1 was nearly identical to the league average (he called a run on 80% of plays, compared to the 78% mean).  With Miles Austin and the newly-acquired Dez Bryant both athletic play-makers who thrive at getting deep, we would love to see the Cowboys employ a more balanced 2nd and 1 approach in 2010.

The chart also provides the run/pass ratio for all plays with a distance-to-go of three yards or less.  You can see that Garrett rarely exploited the high-reward opportunity of short-yardage 2nd down plays.  In fact, the Cowboys attempted just three passes of 15+ yards all season in 2nd or 3rd and 3 or less (3.22% of all plays in these situations).

We would actually like to see the red and blue lines in the graph to the right alternate places in 2010 (or at least move closer together).  A higher pass percentage on 2nd and short and a higher run percentage on 3rd and short, we believe, would result in not only more 1st down conversions for Dallas, but also (more importantly) a much larger opportunity to score quickly on big plays.

For an offense that tallied the second-most yards in the NFL in 2009 yet failed to crack the top 10 in points (14th), maximizing upside through the implementation of high-reward plays in short-yardage situations (particularly on 2nd down) may be just what the doctor ordered for the ‘Boys.