Carson Palmer has had a very good career. He first started with the Bengals at age 25, and was a very good quarterback from ages 26 to 28. Over the next 3 years, his play declined to more solid levels, before holding out in Cincinnati and eventually being traded to Oakland. With the Raiders, Palmer was productive at ages 32 and 33, before moving on to Arizona. There, he was productive again at ages 34 and 35, with the latter season being cut short after six games due to a torn ACL. Then, at age 36, he had a career year, with an MVP-caliber season.

Palmer averaged 8.41 Adjusted Net Yards per Attempt last year, which was even better before an ugly performance in a meaningless season finale. The league average was 6.26, and if you define replacement level as 80% of league average, then replacement was 5.01 ANY/A. Palmer had 562 dropbacks last year, and was 3.40 ANY/A above replacement; that translates to being 1908 Adjusted Net Yards above replacement. I used that methodology to chart every season of Palmer’s career; as you can see, 2015 was the best season of his career

From 1970 to 2003, there were 112 quarterbacks who entered the NFL and threw at least 1500 career passes. I used the above formula to determine each passer’s best season in terms of adjusted net yards above replacement. The chart below shows how many quarterbacks had their best season at which age:

There are not many quarterbacks whose best seasons came at such a late age. Palmer, of course, is one of the three players who had their best year at age 36: the other two were Doug Flutie and Steve DeBerg. At age 37, the two entries are Rich Gannon, which makes sense, and Peyton Manning, which is only because we are using replacement and not average as the baseline. Gannon’s best four seasons, in order, came at ages 37, 36, 35, and 34. The one entry at age 38 is Phil Simms, whose best two years came at ages 35 and 38. And the one man at age 39? That is Jim Plunkett.

On the flip side, Dan Marino and Tim Couch were the two players who had their best seasons at age 23.

If you’re a Palmer fan, the results here can both show how much of an outlier Palmer is, but also might be considered inspiring. Peyton Manning was really good at age 36 and then historic at age 37; Gannon and Steve Young had great years at 36, and then were even better at age 37. The same goes (with a slightly lower baseline) for John Elway, Kurt Warner, and Tom Brady. Supporting cast is undoubtedly a big part of this, and Palmer seems to be playing with one of the best ones. The wildcard in the room is how much his meltdown in the NFC Championship Game impacts him mentally.

The general rule of thumb, I think, for an older quarterback is to project them to be OK until they aren’t. What does that mean? Well, I think of Adam Harstad’s mortality tables. Just because a quarterback is old doesn’t mean he’s going to have a 5 or 10% decline: guys like Manning, Gannon, Young, Elway, Warner, Brady, and Brees are examples of that. But once that decline hits, it’s often severe and permanent. For now, though, Palmer is still one of the rare quarterbacks who had his best season at age 36.