There’s a popular theory in the football analytics community that quarterbacks tend to reach an age in which their passing efficiency drops drastically indicating they are no longer viable NFL quarterbacks. It’s called the QB Age Cliff theory and the idea is a misconstruction of the research of ESPN analyst Brian Burke. Burke discovered that as established quarterbacks age: “all of sudden, one year, their numbers just seem to fall off a cliff”. The word “seems” is important here. Burke also articulates: “there’s no guarantee that the downward trend would continue… regression to the mean says that the following season is more likely going to be an up-year, at least relative to the previous one.” This is the most important part and the part that no one seems to realize.
The narrative Burke was trying to profess through his research is that quarterbacks are more likely to end their career on a down year whether by their own doing or that of their team’s front office. This has nothing to do with falling off a cliff. The idea of a cliff fall is that once you fall, you don’t get back up. That’s how cliffs work.
Well I have news for you: there is no cliff. Never was, never will be. You’re just as likely to fall off the QB Age cliff as you are the edge of the world. Quarterbacks might certainly decline in productivity with age – but just like mother earth – quarterback decline is round.
With free agency coming around the corner, four perennial starting quarterbacks are all coming off down years making some wonder if they found their edge. This group includes Tom Brady, Philip Rivers, Aaron Rodgers and Drew Brees. Here is a quick peak at their 2019 difference in adjusted net yards per attempt (ANYA) from 2018:
Aaron Rodgers -0.25
Drew Brees -0.14
Philip Rivers -1.47
Tom Brady -1.02
It’s easy to buy into the warped idea of some age cliff when you look at how our elder star quarterback faltered in 2019. But a fresh look at the data should give little reason to think either of these four quarterbacks are completely washed. That’s what this analysis is about. To do this, I pooled all quarterbacks into a data set that met the following criteria as done by Burke:
- Modern era only (no QB who played prior to 1978)
- 100 pass attempts per year with at least ten seasons played
- Currently retired
Qualifying QBs
This leaves us with 45 qualifying quarterbacks to search for an age cliff from. But even these perennial starters were not consistent in year-over-year ANYA or any other respected quarterback metric:
Yards per Attempt 0.74
Net Yards per Attempt 0.74
Adjusted Net Yards per Attempt 1.12
QBR 13.5
This is important because if we expect a difference in 1.12 ANYA one way or the other per year, it’s impossible to call a decline in ones final year to do some mystical cliff. What is consistent is the reliability of the variances above when expanding the sample. If we were to increase the sample of quarterbacks to include all those who played at least 5 years instead of ten, the resulting figures are largely the same. There’s also no difference at all in ANYA if we take out each quarterback’s final year to control for some mystical cliff skewing the figures.
Let’s graph all this out. We’ll take these 45 qualifying quarterbacks and bring qualifying non-retired quarterbacks into the fold as well. This way we can compare the current elders with comparative quarterbacks of the past. The graphs below plot each quarterback’s seasonal ANYA across their career plotted on age. A blue regressed trend line is added on top of each and the dashed line shows the NFL ANYA average for 2019 as a frame of reference:
Graph Takeaways
Peyton Manning \ Tony Romo: OK QB Age Cliff truthers, I’ll give you Peyton Manning. That is one steep drop. I’ll concede that old quarterbacks who undergo major neck surgery and literally cannot feel their fingers while throwing a football at age 39 are subject to a cliff fall. Tony Romo had the next most drastic drop for his final year at age 35. But let’s be real, if this was a cliff they fell off of, it was a medically broken spine cliff, not an age cliff.
Drew Brees: Despite his (slight) ANYA decline in 2019, Brees is actually on an upward trend as he hits the big 4.0. this year. I expect the Saints to be right in the Super Bowl conversation again in 2020.
Aaron Rodgers: If an age cliff exists, this is what it would look like. At 32, Rodgers dropped pretty hard and despite a few attempts to re-summit, Rodgers has never gotten close to what he once was. Jim Harbaugh followed a very similar path at age 33. But I find it quite hard to believe age was a primary factor in a 32 and 33 year olds’ sudden drop in performance.
Two examples out of forty-five is not exactly compelling evidence for the existence of an age cliff. You might try making the case that Jim Kelly is a third, but his decline was just coming down from a couple outlier high points. And sure, you can find plenty of quarterbacks with a somewhat drastic final year drop (Marino, McNabb, Plummer, Gannon, McNair, Testeverde, etc.), but without any evidence of sustained lack in production on par with Rodgers or Harbaugh, these declines are all within the reasonable range of variance.
What Does All this Mean for Elder 2020 QBs?
It means that despite down years, there’s no reason to assume this was from anything other than variance. Also note that each and every one of these four quarterbacks are still above the NFL average in ANYA, suggesting they still have plenty left in the tank. Perhaps for Rodgers, slightly above average is all we can expect from the once MVP caliber gunslinger. For Brees, despite struggling in the playoffs, I expect him to keep the Saints in the Super Bowl conversation.
As for teams in a win-now situation? They should be more than happy to throw top dollar towards Brady or – to a lesser extent – Rivers, and hope 2020 brings these perennial studs a sudden ascent from the depths of a cliff that was never even there.
