SUMMARY

We are often asked by customers, “How should I change my betting strategy with the new NFL extra point rules?” This is great question. The betting public, and your sports book, don’t know how coaches are going to react to the new rule. Will the extra distance for extra points prompt coaches to go for two more often? How should we bet on Over/Under bets? At Hooded Rhino, we’ve done this analysis using a rediculous amount of data, and we have incorporated the data into our statistaical models. This article shares our conclusions on the new rules and effects on scores.

THE RULE CHANGES

Before we look at the numbers, we need to understand the rule changes. Prior to the 2015 NFL season, teams were given an option for extra points. They could either attempt a kick worth one point or attempt to score a 2-point conversion by rushing or passing the ball into the endzone. Both attempts were made from the two yard line. Almost all coaches opted for the safe 1-point play until the game was near completion and urgency dictated the more risky two point play. In 2015, the NFL changed the rules. The distance for the 1-point kick is now moved to the 15 yard line, making it more risky. The distance for the 2-point play remains at the 2 yard line.

Prior to 2015, the general strategy was to take the “automatic” point by kicking the extra point until late in the game when strategy dictated more risk in the two-point play. To understand the math behind the strategy, let’s look at some data.

EXPECTED POINTS

In our data set, we have 18315 attempts at extra point kicks since 2000. In the datset, 98.85% of the kick attempts were good from the two yard line (about a 20 yard field goal). When we look at two-point conversions for the same time period, we see that 48.01% of the conversions were successful of 1006 attempts.

Using this probabilities, we can calculate the optimal play for a point after attempt.
The expected value is the amount of points we should expect from the play given the probability of success

E(kick) = 1 x 0.9885 = 0.9885 points
E(2-point) = 2 x 0.4801 = 0.9602 points

As you can see, the kick attempt is almost 99% effective. That is, over the course of a season, the team can expect to get 98-99 points on 100 extra point kick attempts. Conversely, the same team would expect only 96 points if the attempt 100 2-point conversions.

You are probably thinking that two points over a season is not a big difference, but our sample size isn’t that large. Let’s see what happens if we include all rushing and passing plays from the same 2-yard distance at the goal line. In this data set, we have 3959 records with a touchdown success rate of 0.31%. Combining the two sets, regular touchdown attempts and 2 point conversions from thw 2 yard line, we have a 0.35% success rate.

Now the expected value can be calculated as
E(2-point) = 2 x 0.3454 = 0.6908 points

This is the figures that the coaches see. On average, the touchdown plays from the two yard line is only 35% effective. And the extra point attempt is 99% effective. They stand to make 30 more points by kicking extra points over 100 attempts.

WHAT HAPPENS WITH THE NFL RULE CHANGE

Now that we see how the expected value can be used to chose the most optimal play, lets see what happens when the ball is moved to the 15 yard line for point after attempts for kicks.

We don’t have any data on 15 yard point after attempts. However, we have data on field goals. We can use the success rate on 32 and 33 yard field goals to estimate the success rate of the new point after attempts. I know what your thinking: field goals can be kicked from the left and right hashes, whereas extra points are kicked from the center of the hashes. That is true; however, by using field goals in this way, any success rate will be the worst case. Kicking from the middle of the field will have a higher success rate.

In our data, we have 967 attempts at the 32-33 yard range. Some teams line up a kick at 7 yards beyond the line of scrimage, while others line them up at 8 yards. The success rate is about 90.07%.

The expected value of the new extra point is
E(new-kick) = 1 x 0.9007 = 0.9007 points

With the new rules, a team can expect 90 points out of 100 extra points attempts.

Conclusion

Looking at expected values, we can see that the conversion rate for kicking extra points at 15 yards provides a 90% probability, whereas, 2 points conversions will provide 69 poins out of 100 attempts. Hooded Rhino predicts that coaches will remain confident in kicking extra points and will opt for them throughout the game. Additionally, since 1 out over 10 extra points will be missed, we expect the “desperation” factor will increase, and we expect some coaches will gamble on 2 point conversions around the early 4th quarter. Also, some coaches will opt to “make up” for missed extra points. In our calculations, this will tend to have about a 1 point addition in over/under scores. the trick will be whether Vegas makes the same adjustments in their over/under calculations. We will have to see.