Best Games of the Decade

Check out the Win Probability graphs and play-by-play of your favorite team’s biggest comebacks and most exciting games since 2000. An explanation can be found here. Just select a year, a team, or ‘any’, and start clicking:

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Sep 16, 2009
The 4th Down Study – Part 4

The is the fourth and final part of my article on 4th down decisions. In the first part, I reviewed the concept of Expected Points and the concept of expected utility. The second part detailed the kicking game and its expected values. The third part explored the value of 4th down conversion attempts. This, the final part of the article puts all the concepts together. I also discuss some of the explanations for why coaches are so reluctant to go for it when they should.

Putting It All Together

To build a chart of general recommendations where teams should go for it or kick, we can simply repeat the analysis from Part 3 for each yard line and distance to go. We’ll start by plotting the EP values for kicks from various yard lines. First, here are the values for punts:

And here are the vales for FGs:

The graph for ‘go for it’ attempts is a little trickier. While punts are the same value regardless of distance to go, the value of a conversion attempt is highly dependent on it. The colored curves plotted below correspond to the EP values for each distance to go.

Now, let’s put it all together and overlay the graphs for the kick values. (Click on the graph to enlarge).

Wherever the value lines for the conversion attempt are above or overlap the value lines for kicking, the decision should normally be to go for it. Remember, we assumed a successful conversion would be exactly at the first down marker and no further, which means the tie goes to ‘go for it.’ The final graph below charts the recommended option for each field position and distance to go combination. On the line or below it, a coach should go for the 1st down.

That chart is the bottom line, the take-away. It says that coaches should normally be far more aggressive on 4th down.

So Why Are Coaches So Stubborn?

If the benefit of going for it is so clear, why are coaches choosing to kick so often? The authors of Hidden Game of Football suggest that the current 4th down doctrine in football is a hold-over from the early days of the sport. Back in the day, teams were lucky if they mounted one successful scoring drive all game. A good punt virtually ensured the opponent wouldn’t score on their ensuing possession.

David Romer’s explanation goes a step further. He suggests that coaches are thinking more about their job security than their team’s chances of winning. Coaches know that if they follow age-old convention by kicking and lose, then the players get most of the blame. But if they defy convention and go for the 1st down and fail, even if it was the best decision, they’ll take all the criticism.