Last May, Chuck Zodda examined the rule change that pushed extra points from the 2-yard line to the 15-yard line, and the data analysis showed a likelihood that kickers would connect at a 92.7% rate. Through four weeks of the season, NFL kickers are on track to make 94.1% of the longer extra points. Will this hold up?
Shortly after the NFL Draft in the spring, the NFL Competition Committee voted to push extra points (XPs) back 13 yards in an attempt to add excitement to a play that had previously been an extension of commercial breaks for many fans.
Through four weeks, NFL kickers have connected on 285 of 303 kicks, good for 94.1% accuracy. This number is slightly higher than the predicted 92.7% for one reason: NFL kickers have the choice of where they place the ball between the hashes on extra points. Field goals are required to be placed on the hashes if the previous play ended outside the hash 
marks, or where the play ended if it occurred inside the hash marks. Extra points allow the choice of kicking angle. Kickers will naturally select a location on the field they feel most comfortable, resulting in a slight uptick in accuracy.
Broadcasters, fans, and journalists have noted that the increased accuracy has coincided with the majority of games being played in good weather. The assumption is that it may be more difficult to make XPs from the longer distance during the colder part of the schedule in November and December. A casual glance at the data might even seem to confirm it. However, this is not borne out by the historical data.
According to pro-football-reference.com from 2000-2014 there were 6,629 field goals attempted during weeks 1-8 of the NFL season. Kickers hit the target on 5,458 of those, good for 82.3% accuracy in the first half of the season. In weeks 9-17, kickers were 6,298 for 7,765, pushing their accuracy down to 81.1%. This might suggest that accuracy on XPs would fall over the second half of the season.
Much of the reduction in accuracy is due to longer kicks. Over the same 15-year period, kickers went 996 for 1,166 (85.4%) on kicks from 32-37 yards in weeks 1-8, and improved slightly to 1,228 for 1,432 (85.8%) in weeks 9-17.
Looking at kicks from 38-57 yards, kickers went from 72.2% in the first half of the season, down to 68.7% in the second half of the season. Thus, most of the decline in the latter months of the season is due to greater difficulty with long-distance attempts, rather than the type of kicks we see on XPs.
Another consideration is selection bias: Do NFL coaches go for it more on fourth down in the latter months of the year in order to avoid kicking in bad conditions?
The data shows this is not the case for XP-distance field goals. From 2000-2014, NFL coaches went for it on fourth down 23.8% of the time during weeks 1-8 when the ball was inside the opposing 40-yard line. In weeks 9-17, that percentage rose to 26.3%. However, the average yards required for a first down in this situation decreases from 4.29 in weeks 1-8 to 4.26 in weeks 9-17, indicating coaches are likely going for it more often because they require slightly less yardage on fourth down. More importantly, when corrected for field position, there is another clear trend that shows up. When the ball is inside the red zone, NFL coaches went for it 19.6% of the time during weeks 1-8, and 19.5% of the time during weeks 9-17. There is no statistical difference here.
Where the difference shows up is once again in longer kicks, where coaches went for it 27.6% of the time on kicks between 38 and 57 yards in weeks 1-8, but ramped up to 33.9% in weeks 9-17. This data clearly indicates that we have not seen a skewed sample on the type of kicks that XPs represent. We are seeing a true picture of what we should expect in the second half of the year.
While many people have made the argument that extra points are going to get more difficult as the weather turns colder and snowier, the statistical data from the last 15 years shows this to be unlikely. In fact, I believe we are more likely to see an increase in accuracy due to greater comfort with the new distance over the course of the season, rather than a decrease.
Follow Chuck on Twitter @ITP_ChuckZ.