Re-Analysis of 4th Down Attempts: The Impact of Momentum
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.
- Don’t punt on the opponent’s side of the field.
- Really consider going for it on 4th down after crossing your own 40.
- 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.
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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