Tom Brady is Old: 2021 Snap-Weighted Age

NFL Offseason - After poring over the data and carefully running our calculations, Football Outsiders is fairly confident we can take one clear conclusion from the 2021 NFL season: Tom Brady is really old.

Yes, it's time once again to go through our snap-weighted age (SWA) data, calculating a team's age not by just averaging the ages of the players on the roster, but by weighting the age of each player by the number of snaps he played in the regular season. We have been tracking this since 2006, which allows us to have a fairly good impression of the trends in roster construction and player development we have seen over the past decade and a half.

And in that time, no player has had a greater effect on a stat as Tom Brady has had on SWA. We devoted nearly half of last year's article to the effect of his movement from New England to Tampa Bay, as his departure led the Patriots to having the largest ever year-over-year decrease in offensive SWA. As for 2021, the Tampa Bay Buccaneers had both the oldest team and the oldest offense in the league, the third time in the last four years Brady's team has had those distinctions. And the longer Brady plays, the more Brady just totally obliterates the stats.

It's not like the rest of the Tampa Bay team were spring chickens last season or anything, but remove all quarterbacks from SWA and the Buccaneers would fall to eighth oldest in the league. Brady by himself increases Tampa's SWA by 0.6 years; that alone is more than the difference between the first-place Buccaneers and the fifth-place Titans. On offense, Brady increases Tampa Bay's SWA by 1.5 years; that's more than the difference between the first-place Buccaneers and the eighth-place Texans. We have never seen anything quite like this. At 44 years old, Brady was the oldest player in NFL history to start double-digit games. He broke the previous record, set by Tom Brady, which itself broke the previous record, tied by Tom Brady. There have been 23 fortysomethings who have started double-digit games; five of them have been named Tom Brady. And now he's coming back, and we'll likely have this same conversation next year, and the year after that, and the year after that, until either Brady or the planet Earth crumbles into dust. Sportsbooks have Brady +250 on that competition.

But it turns out that 31 other teams did play football last season, so we should probably talk about them, too. So let's dig in to the numbers a little deeper.

2021 Snap-Weighted Age: By Unit

The following table shows SWA for the overall team (TOT), along with the unit breakdown for offense, defense, and special teams. Units are ranked from oldest to youngest.

In 2020, year-to-year correlation in SWA dropped dramatically, in part due to COVID shuffling rosters, and in part due to both Tom Brady and Philip Rivers changing teams and dramatically altering the age composition of the Patriots, Buccaneers, Chargers, and Colts. The COVID vaccines helped squelch the first factor; both defense (.57) and special teams (.76) year-to-year correlations bounced back significantly in 2021 as teams didn't have to rely on quite so many street free agents to fill holes caused by infections.

But year-to-year correlation on offense? It was still pretty low. There was just a 0.34 correlation between 2020 and 2021 SWA on offense as multiple teams around the league saw massive year-to-year swings.

Just like last year, we can see some player movement reflected in the overall numbers. The Matthew Stafford trade was enough to shoot up the Rams' numbers by itself as the 33-year-old Stafford replaced the 26-year-old Jared Goff under center for the Super Bowl champions. The Lions didn't limit themselves to just replacing Stafford, mind you, as out went thirtysomethings Marvin Jones, Danny Amendola, and Adrian Peterson. Those sorts of players have no business being on a rebuilding team, and replacing that foursome with guys like Goff or Amon-Ra St. Brown explains why the Lions got so much younger offensively in 2021.

Alejandro Villanueva moving from Pittsburgh to Baltimore shows up here too; offensive linemen can have a large impact on SWA because they don't get rotated out like skill position players might. Along with Villanueva, the Ravens brought in Kevin Zeitler. Both thirtysomething linemen started all 17 games for Baltimore last season, a year after the Ravens had the second-youngest line in the league. They also got about 400 snaps out of 31-year-old Latavius Murray, which was very much not in the plan for Baltimore before their entire running back room got injured. As for Pittsburgh, they let Vance McDonald go and got lots of work from rookies Pat Freiermuth, Kendrick Green, Dan Moore, and Najee Harris; I'd expect their numbers to go down even more next year with Ben Roethlisberger finally retiring.

The other two teams are here because of different directions on the offensive line. The 49ers got older, bringing in Alex Mack and getting more snaps out of Trent Williams, both of whom made the Pro Bowl. The Raiders got younger, jettisoning Rodney Hudson and Sam Young and running with a line with five primary starters all age 26 or younger.

It seems like team offensive age is going to continue to fluctuate significantly next season. We have seen a crazy amount of movement this offseason already: the quarterback carousel spinning, huge wide receiver trades, and the like. The success of the Buccaneers and Rams in the past two seasons have inspired more teams to take swings and bring in veterans; only time will tell if this is the new dominant strategy, or if it's just coincidence that two teams brought in new veteran quarterbacks and hoisted hardware the next season.

As for the Lions, they ended up as the fourth-youngest team in SWA history, behind the 2017-2018 Browns and the 2018 Cowboys. The offensive drop we talked about made them the third-youngest offense behind the 2017 Browns and 2014 Jaguars. They also shed a year of SWA on defense, with only Nick Williams and Michael Brockers as over-30 starters. They lost 1.26 years of SWA overall; they basically got rid of everything not bolted down as part of a full-fledged rebuild. It dropped them from 12th to 32nd in SWA as they look towards the future. It's not as big as the Brady-influenced youth movement in New England a year ago, but it is the 12th-largest drop since 2006; a full escape from the Matt Patricia era. And not a moment too soon.

It's no surprise that the Buccaneers were the oldest offense in the league; they're also the 27th-oldest offense in league history as Rob Gronkowski, Ryan Jensen, Cameron Brate, Giovanni Bernard, and Josh Wells were all contributing thirtysomethings behind Old Man Brady. But the Titans were only just behind them as the 32nd-oldest offense we have ever recorded. Ryan Tannehill is no Brady, but he was still 33 years old last season, and four of the linemen were thirtysomethings as well. That should change for 2022; it looks like David Quessenberry will not be re-signed, and Rodger Saffold went to Buffalo. A youth movement was definitely needed along that line, as all that age and experience still led them to being just 16th in adjusted line yards and 26th in adjusted sack rate in 2021.

But we need to talk about the Patriots. Only the Buccaneers were older than New England was last season, and that's entirely because New England started a rookie quarterback all year long. Take out passers, and New England's 27.5 SWA would be the oldest in the league. The Patriots had the oldest defense in the league for the second time in the past three seasons, and they have now ranked in the top five in each of the past four years. They also have the oldest special teams unit ever, finally taking the crown from the 2006 Saints with a SWA of 28.7. The Patriots have led the league in special teams age for each of the past four seasons, but took a huge step forward in 2021, gaining 1.2 SWA on their way to taking the crown. They had four different thirtysomethings—Matthew Slater, Cody Davis, Justin Bethel, and Brandon Bolden—with at least 250 special teams snaps. The rest of the league combined had 11, and no more than one per team.

Part of the aging special teams is by design; Bill Belichick values his special teams stars and prioritizes keeping them in a way few other teams do. There's a reason the Patriots had positive special teams DVOA every year from 1995 to 2020 before falling to -0.046% in 2021. But part of it is the result of three or four years straight of subpar drafts, failing to find the sorts of players who would be filling in in the linebacker corps, or the secondary, or yes, the punt and kick units. We're finally beginning to see a bit of a change there with Kyle Duggar and Ja'Whaun Bentley playing significant roles last season, but it will take a while for the effects of a run of bad drafting to really work its way through; the Patriots are heavily reliant on veterans for reasons besides just valuing experience.

2021 Snap-Weighted Age by Position

Not all teams are old in the same ways. Because offensive SWA is so affected by the offensive line, and defensive SWA tends to give teams with young secondaries an advantage, it can be useful to see where teams are young or old in particular.

The following table lists every team's SWA in each positional group and is fully sortable. The colors trend from red (older) to blue (younger). Note that this is the first year we have split out snap-weighted age for edge rushers separate from interior defensive linemen or linebackers. The special teams number here differs from the special teams number above because on this table it only includes specialists (kicker, punter, and long snapper) instead of all special teams snaps by all players.

Being younger than average at every position is a rare feat, but the Lions just barely pulled it off. Their defensive line was 0.085 years (about a month) younger than average. They may get even younger there next season as they don't seem to have any interest in re-signing the 32-year-old Nick Williams.

No one was older than average at every position, but the Titans sure made a run for it. They were particularly old at quarterback, tight end, offensive line and on special teams, but they were saved from running the table by the youngest defensive line in football; their top four interior line players (Jeffery Simmons, Teair Tart, Naquan Jones and Larrell Murchison) were all 24 or younger.

Three teams managed to be the oldest in the league at two different positions. The Cardinals were deans in the league at both edge rusher and special teams; I don't think there's any particular reason for concern that Matt Prater and Andy Lee are old, but they should get younger off the edge with Chandler Jones out of town. The Patriots were the oldest in the league at both linebacker and defensive back, so the arrivals of Duggar and Bentley weren't enough, in and of themselves, to entirely rejuvenate an aging back seven.  And then there were the Buccaneers, with Rob Gronkowski's tight ends and Tom Brady's quarterbacks outpacing the rest of the league.

And, yes, Brady stands out like a sore thumb. The Buccaneers were a record 15 years older than average at quarterback and 5.6 years older than any other team. They up the league's average by 0.5 years all by themselves. Brady will continue his war against time for at least one more season, and we'll be back to cover it in this article 12 months from now. Again.