Friend of the program Bryan Frye is back for another guest post. As regular readers know, Bryan operates his own fantastic site, http://www.thegridfe.com. You can view all of Bryan’s guest posts here, and follow him on twitter @LaverneusDingle.
Floating around the internet, there are copious metrics for measuring quarterback performance. Some are very basic (passing yards, completion rate), while others are quite complex (EPA, WPA). Some are open-source (passer rating, ANY/A), while others are proprietary (DVOA, Total QBR). It seems there is a stat to cover just about every aspect of QB play, so the last thing we need is another useless number.
Well, I didn’t get that memo.
Today, I’m going to look at a somewhat abstract measurement for career value, based on adjusted yards per attempt relative to league average. I prefer ANY/A and my own TAY/P (and the different iterations of both metrics), but gaps in the record books mean we can only go so far with either. With AY/A, we can go back to 1932, the very first season of the “official stat” era in the NFL.
The methodology is simple and straightforward. I took Pro Football Reference’s AY/A Index Scores for every quarterback with at least 1500 career pass attempts. If you are familiar with PFR’s advanced passing stats, you know they are based on three seasons’ worth of data (years n-1, n, and n+1), and a score of 100 represents league average output. To find the AY/A+ score itself, you simply multiply a player’s z-score by fifteen and add the product to 100. Using this knowledge, I reverse engineered the passing Index Scores in order to find the number of standard deviations above or below average each quarterback’s AY/A was. I then multiply that number by pass attempts to come up with an abstract career value metric. I also did this for replacement level, using one standard deviation below average as the baseline for replacement play.
Value over average = [(AY/A Index Score – 100)/15]*Attempts
Value over replacement = [(AY/A Index Score – 85)/15]*Attempts
Like I said, this isn’t forking any lightning in the realm of quarterback analysis. It’s just a quick and dirty way to approximate career productivity based on a well-known metric.
The table below shows the abstract career value of the 182 quarterbacks who met the 1000 attempt threshold. Read it thus: Peyton Manning played 266 career games and had 9380 pass attempts. His career AY/A+ score was 116. This gives him a total value of 10005 above average and 19385 above replacement (this is the metric by which the table is sorted). Note that the table below does list all 182 quarterbacks, but for ease of scrolling, only the top 25 are displayed by default. You can change that using the dropdown arrow on the left, or you can search for your favorite passer.
I normally like to point out a few curiosities I notice in the data, but I’d rather just present the numbers and leave the comments to the readers. What sticks out to you? Oh, and one note: back in 2006, Chase did some back-of-the-envelope calculations that had Rick Mirer as the worst quarterback of all time. 10 years later, not much has changed.