Sometimes when I'm listening to the radio, a song will come on that I haven't heard in years. It might be totally innocuous, a stupid pop song that had spent a few weeks on the charts when I was in high school, but instantly it reminds me of a moment in time when I first heard it. I can sometimes remember who I was with, where I was, how I was feeling; that nostalgia floods back with songs like Josh Gracin's "We Weren't Crazy" or Dashboard Confessional's "Hands Down".

The thing is, these memories are often foggy with the haze of time and distance, and the complexity of those people or events gets lost. We all tend to glaze over the muddier parts of history and make it neater and simpler in our minds. This is how many people view the legendary career of former Green Bay Packers, New York Jets, and Minnesota Vikings quarterback Brett Favre.

The Packers announced that the former superstar will be inducted into the team's Hall of Fame and have his jersey retired, so I decided to look back on Favre's career and really determine just how good he was. Here at numberFire, we don't dwell in nostalgia or narrative; we use in-depth statistical analysis to break down player performance. Today we'll find out if, despite the scandals and betrayal, aside from the rings and awards, Brett Favre is one of the greatest quarterbacks of the modern era.

Just A Number

The great Negro League baseball pitcher, Satchel Paige, who pitched until he was 45, was once asked about his performance at an old age. He responded, "How old would you be if you didn't know what age you was?" The simplicity of his response belies an important idea: sometimes age is just a number; what you do on the field is much more important.

However, our task today with Brett Favre isn't just to admire his records and titles. Playing 20 seasons in the NFL, Favre holds most of the league's career passing records, and still played at a very good level until he retired at age 41. How does this late age performance measure up against other passers of our time, and is Favre truly the greatest quarterback ever?

To break down his career, we turn to our in-depth signature metric, Net Expected Points (NEP). NEP is a measure of how much a player advanced his team’s of scoring on any given play, measured in expected points. Specifically, with quarterbacks, we'll look at Passing NEP. This facet of NEP is the total of any value gained or lost on any drop back by the quarterback.

However, there's a small wrinkle we're adding in for this study. Since Favre played at such a valuable level for so long, we also want to know how to value such immense late-career production. To do this, I applied an age-weighted system to modify our quarterbacks' values and more properly compare, say, Carson Palmer's age 32 season and Doug Flutie's age 42 one. We'll delve more into this a little later.

Raw Talent

First, let’s take a look at Favre’s numbers via NEP since the year 2000, the season our numbers typically date back to. This is still is a good snapshot of the second half of his career, which is what we'll focus on regardless (more on that later). The table below displays his annual Passing NEP, Passing NEP per drop back, and his rankings by year for these metrics.

From play to play, and clearly from season-to-season, inconsistency was the name of the game with the gunslinging Favre. In terms of raw Passing NEP, Favre rose to third in the league at his best, and in five of his last 11 years in the league, was a top-10 quarterback by Passing NEP.

However, almost every one of these was alternated with a 15th to 25th place finish within the metric. Interestingly, Favre’s efficiency always seemed rough at best, but on a per drop back basis, he matched or surpassed his Passing NEP rank in this metric six of eleven times; while clearly a volume passer and a risky thrower, this shows that he wasn’t just these things. He was a complete quarterback.

For historical context, among all quarterbacks with at least 100 drop backs in a season since 2000, Favre’s best three seasons in the second half of his career rank 20th, 39th, and 42nd. In comparison, Peyton Manning owns the 1st, 5th, and 7th, while Tom Brady has the 2nd, 6th, and 11th. In terms of raw NEP, Favre was a great quarterback for his time but certainly never “the best”, and efficiency and consistency were always bugaboos for him too. When matched up against other quarterbacks’ best seasons, he clearly pales in comparison to titans playing today like Manning, Brady, Aaron Rodgers, and Drew Brees. But what if we examine the fact that these seasons came when Brett Favre was well over 30 years old?

Respect Your Elders

I created – with the guiding eye of my friend, Fake Pigskin analyst Jay Holmes – a linear weights system to adjust the raw Passing NEP of each quarterback in our study to account for the age they were when they produced these numbers. In college scouting especially, this is called “age-weighted production”, but I wanted to apply it to senior citizens instead of seniors in school.

To do so, I plotted each quarterback’s age and then found the average age among all starting quarterbacks over the past 10 years. This large of a sample would account for rookie turnover as well as aging veterans, and our average age of 28.4 for a starting passer in the NFL since 2004 sat right in the middle of the two.

From there, I took the population of our study and figured out what each age’s standard deviation from 28.4, our average, was. Multiply the player’s Passing NEP by this modifier and add it to the raw NEP score, and thus, we had an age-based modifier that would reward prolific seasons more at a later point in a player’s career.

I wanted to look solely at the older age seasons so that we could see just how well Favre’s late career matched up, so for passers with more than 100 drop backs and age 30 or older, we had a sample size of 169 quarterback seasons to look at. The table below shows the top 10 seasons by age-weighted Passing NEP, along with the player’s age, Passing NEP, per drop back efficiency, and weighted versions of these metrics. The results are pretty stunning.

There are a couple of fascinating things about this table to note quickly. The first is that only five quarterbacks populate it, and three of them own eight of these top-10 seasons, in Manning, Brady, and Brees. Aside from Favre, Rich Gannon is the only other entrant here. The youngest season on this table is Brady’s age 31 season in 2007, when he set a new passing touchdown record. This didn't receive nearly the age-weighted bonus that others did, but was impressive enough in its own right to make the top 10. Also notable was Gannon’s highly effective campaign at age 37 in 2002, which – while not as prolific in raw Passing NEP as the others – receives a lot of weight for being performed by that old of a player.

But we come back to the question: how good was Favre? Considering that his best season by NEP came at age 40, I’d say he was pretty darn good. Registering the 20th best season since 2000 at an age over 40 will win you a lot of points in this system, and sure enough, Favre’s performance is the second-best ever in the old man’s NEP bracket. It’s also interesting to note that, while Manning and Brady own three top-10 seasons each, Favre’s 2007 campaign (age 38) comes in at 11th in age-weighted Passing NEP, and his 2004 (age 35) is 22nd on the list. Still, we can't deny that one season of explosive production does not make his career is one of sustained excellence like Manning's or Brady's has been.

A Golden Jacket

Was Brett Favre the greatest passer of our time? No, but he still was clearly one of the best to ever play the game. Most of the impressiveness of Favre’s career comes from the fact that he was an absolute iron man and racked up counting stats. The raw metrics show that he was very good for many years, but he doesn't deserve to be at the forefront of the quarterback line in NFL history based on his performance. He does, however, deserve to be among their company for the age-defying feats he accomplished. For these achievements, we should celebrate him.