Jacob Long has an outstanding pair of posts on evaluating kickers in the NFL. FIrst up is the analysis itself:
Justin Tucker is so great that, quite frankly, it doesn’t matter which metric you use. PAA, FG% – eFG%, or just plain old FG%, he’s unlike anyone else in the past 10 years. Given the well-documented trend of increasing kicker accuracy in the NFL, I think Tucker has a solid claim on being the greatest kicker of all time.
Even with fewer seasons than many of his competitors, his PAA are double all the others who kicked in the past 10 years. He had a slightly more difficult than average set of attempts but made a higher percentage of his attempts than anyone who has had more than 22 tries. Good luck trying to find any defect in Tucker’s record.
Jacob then covers the method in detail:
Pasteur and Cunningham-Rhoads — I’ll refer to them as PC-R for short — gathered more data than most predecessors, particularly in terms of auxiliary environmental info. They have wind, temperature, and presence/absence of precipitation. They show fairly convincingly that while modeling kick distance is the most important thing, these other factors are important as well. PC-R also find the cardinal direction of every NFL stadium (i.e., does it run north-south, east-west, etc.) and use this information along with wind direction data to assess the presence of cross-winds, which are perhaps the trickiest for kickers to deal with. They can’t know about headwinds/tailwinds because as far as they (and I) can tell, nobody bothers to record which end zone teams defend at the game’s coin toss, so we don’t know without looking at video which direction the kick is going. They ultimately combine the total wind and the cross wind, suggesting they have some meaningful measurement error that makes them not accurately capture all the cross-winds. Using their logistic regressions that factor for these several factors, they calculate an eFG% and use it and its derivatives to rank the kickers.
Those wind factors make certain stadiums like New Era Field (where Buffalo plays) tricky: it’s fun to see two flags right next to each other pointing in opposite directions, or the flags on the field goal posts pointing hard right, then switching to hard left, then switching back to hard right over the course of a field goal try. H/T R-Bloggers