By Brian Burke
Here's the situation: At the beginning of the 3rd quarter against CAR, NO had a 1st and 10 at their own 16-yard line. They threw for a 7-yard gain, setting up a 2nd and 3 from their 23. But CAR was flagged for defensive holding, which would have given NO 5 yards and an automatic first down at their 21. NO head coach Sean Payton declined the penalty to the bafflement of many including the tv announcers.
The game did not hinge on this decision by any stretch. But it's worth taking a look at. The EP model is probably the right tool for the job in this case because it gives a much finer level of precision to down/distance/yd-line situations than the WP model or other approaches.
Using the hand-dandy WP calculator tool (which as a bonus is also an EP calculator), here are the relevant numbers:
1st and 10, own 21: +0.38 EP
2nd and 3, own 23: +0.58 EP
I checked PFR's EP numbers too, and they are very similar, also favoring the 2nd and 3 over the 1st and 10. [Edit: Keith's model also favors the 2nd and 3.]
It's a very slight difference, but if we're going to trust the numbers it appears that Payton probably made the right decision. These results hold up throughout the length of field, so it's not a quirk of being near a team's own 20. But it's close enough to be near the point of indifference (which would generally be a 2nd and 4 on a 6-yd gain). The results go against my intuition, and I'm not sure why 2nd and 3 plus 2 yards beats a 1st and 10--it just does. The takeaway here is just that Payton didn't make a mistake.
I know some readers who aren't familiar with EP might think it's some convoluted black box statistic, but it's simply the average net point expectancy given down/distance/yd-line situations. It's smoothed to filter out the noise, but that's all that goes into it. Different implementations can have slightly different values depending on what data they include, but the slopes are the generally the same, which is a key consideration. EP is usually only useful in comparison to another EP value, such as the difference between the EP at the snap and the EP at the whistle, which gives us EPA. Or in this case, the important thing is the comparison of the results of an option to decline a penalty.