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Snap-Weighted Age: 2020 NFL Rosters

Tampa Bay Buccaneers TE Rob Gronkowski and QB Tom Brady
Photo: USA Today Sports Images

From: AgeWatcher@FootballOutsiders.com
To: GOAT@TB12.biz
Subject: Please stop wrecking our stats.


2020 was a strange year.

Football Outsiders has been tracking snap-weighted age (SWA) since 2006, 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. Most years, these articles end up covering much the same ground, as consistent trends keep rising to the top. Even 2020 wasn't quite strange enough to break every pattern.

In all but two years, the league's average age has dropped, as the benefit of players on cheap rookie contracts continues to drive roster construction. That was true again in 2020, as we now have a new all-time low league average SWA of 26.4. The oldest team in the league last year wouldn't have cracked the top half of the league in 2006. The current CBA means that it's much more cost-effective to fill out your roster with players on rookie deals rather than savvy veterans, especially on the margins. While there has to be a floor somewhere, we're not there quite yet. Sixty-five rookies started at least half of their team's games last season, and there's no reason to expect that number to drop in the future.

At the same time, almost every year there is a decently strong correlation between the age of a roster and its DVOA, and yes, that was true again in 2020—in fact, 2020 saw the highest correlation between age and DVOA we have seen in over a decade. It makes sense that contending teams would have more veterans on their roster than rebuilding ones; it's fairly normal to be either good and old (see: New Orleans) or young and terrible (see: Jacksonville). Six of last year's 14 playoff teams were among the 10 oldest in the league; only two were among the 10 youngest, and none were below average on both offense and defense. If you're a veteran player who has survived to your second or third contract, you're probably pretty good, and teams with high numbers of good players tend to be good themselves, shockingly enough.

And every year, there's a significant year-to-year correlation in this stat, which also makes sense—old teams tend to stay old. You don't generally overhaul an entire roster overnight; you replace pieces one at a time. The average year-to-year correlation is 0.59, and until this year it had only dropped below 0.50 once

But here, 2020 finally breaks with tradition. With just a 0.40 correlation to SWA from 2019 to 2020—the lowest we have ever recorded—there were some massive swings and dramatic changes to cover across the league. The unusual is to be expected in 2020, a year unlike any other in the league's history. But at the end of the day, a familiar face was responsible for much of 2020's strangeness.


2020 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.

2020 Snap-Weighted Age
Team TOT
SWA
Rk OFF
SWA
Rk DEF
SWA
Rk ST
SWA
Rk
NO 27.3 1 27.4 8 27.5 1 26.7 5
CHI 27.1 2 26.6 20 27.5 2 27.2 3
TEN 27.0 3 27.5 5 26.5 13 27.3 2
ARI 27.0 4 27.2 10 26.9 6 26.5 6
NE 26.9 5 26.4 23 27.3 3 27.5 1
ATL 26.9 6 27.8 2 26.1 22 26.4 9
PIT 26.9 7 27.4 7 26.7 9 25.8 19
TB 26.9 8 27.7 3 26.3 17 26.1 14
SEA 26.8 9 27.4 6 26.6 11 25.7 23
LV 26.6 10 27.4 9 26.0 24 26.5 8
IND 26.6 11 27.6 4 26.0 25 25.7 22
DET 26.6 12 26.8 14 26.6 10 26.1 16
BUF 26.6 13 26.4 22 26.8 7 26.5 7
PHI 26.5 14 26.5 21 27.0 5 25.4 25
HOU 26.5 15 26.9 12 26.3 14 26.1 15
GB 26.4 16 28.1 1 25.2 31 25.3 29
KC 26.4 17 27.1 11 25.9 26 25.8 20
SF 26.4 18 26.7 17 26.2 19 26.2 12
NYJ 26.3 19 26.7 18 26.1 21 26.3 10
MIN 26.3 20 26.7 16 26.0 23 25.8 21
CLE 26.2 21 25.8 26 27.1 4 25.4 26
LAR 26.1 22 26.6 19 26.1 20 24.9 32
CAR 26.0 23 26.8 13 25.2 30 25.9 18
CIN 26.0 24 25.6 27 26.3 18 26.2 13
WAS 26.0 25 26.8 15 25.2 29 25.6 24
BAL 25.9 26 25.0 32 26.5 12 26.8 4
DEN 25.9 27 25.3 30 26.8 8 25.4 27
DAL 25.8 28 25.2 31 26.3 15 26.2 11
LAC 25.8 29 25.6 28 26.3 16 25.2 30
NYG 25.7 30 25.8 25 25.6 28 25.9 17
MIA 25.6 31 25.5 29 25.9 27 25.3 28
JAX 25.4 32 26.1 24 24.9 32 25.0 31
NFL 26.4 26.6 26.3 26.0

There aren't any real surprises at the top of the table. The Saints have been one of the 10 oldest teams in football in seven of the past eight years, as their team-building strategy the last couple of seasons has been to try to keep the old band together as long as possible, pushing out contract hits into the future and using salary cap chicanery to keep everyone around while there was still life in Drew Brees. They had seven players aged 30 or over play at least 500 snaps (third in the league behind the Steelers and Colts), and only 10,238 snaps from players 25 or under (second-fewest in the league behind the Bears). To a certain extent, this has worked—the 2017-2020 Saints are only the fourth team to have a DVOA above 25.0% in at least four consecutive years, in part because of the high level of continuity, plus a willingness to bring in aging free agents to plug holes as they tried to turn that regular season success into a Lombardi Trophy.

Ultimately, this era of Saints teams will be remembered more for postseason failures than anything else, and now the piper has come due—not only is Brees gone, but the Saints also need to replace thirtysomethings such as Jared Cook, Janoris Jenkins, Emmanuel Sanders … the list goes on. At least they have young, sprightly, soon-to-be 31-year-old quarterback prospect Taysom Hill in the wings! The 2021 Saints should look significantly different on this table, is what we're saying.

And speaking of significantly different…

When we first ran the numbers and saw the historically low correlation to last year's results, I chalked it up to COVID problems. Between opt-outs, a lack of a real preseason, various COVID scares throughout the league, the increased roster flexibility brought by the temporary injured reserve and practice squad rules and so on, it would make sense for rosters to be more in flux than in a regular year. And that almost assuredly did play a part, in ways both small and large throughout the league. If you were to arbitrarily eliminate the five biggest year-to-year differences in any given season, to avoid outliers who had particularly active roster movement, 2020's correlation would clock in at 0.62, compared to an average of 0.85 in previous years. Your average rank-and-file team had more uncertainty and change on their rosters in 2020 thanks in large part to the ongoing global pandemic.

But with only 32 datapoints in a given season, a few outliers can swing those correlation numbers one way or another. And boy howdy, do we have some notable outliers. Here's a table of the five teams with the biggest changes between their 2019 and 2020 SWA.

Biggest Changes in SWA, 2019-2020
Team 2019 SWA 2020 SWA Diff 2019 OFF 2020 OFF Diff 2019 DEF 2020 DEF Diff
NE 28.6 26.9 -1.7 29.3 26.4 -2.9 28.2 27.3 -0.9
TB 25.8 26.9 +1.0 26.2 27.7 +1.6 25.6 26.3 +0.6
LAC 26.7 25.8 -1.0 27.3 25.6 -1.7 26.7 26.3 -0.4
IND 25.7 26.6 +0.9 25.0 27.6 +1.5 25.6 26.0 +0.4
DAL 26.7 25.8 -0.8 27.0 25.2 -1.7 26.2 26.2 +0.1

Why am I not surprised that Tom Brady remains a bigger force of nature than the novel coronavirus?

The top five changes from last year are all offensive-driven moves and, if we're honest, quarterback-driven ones. Brady bringing his 43-year-old body down to Tampa Bay in part of his never-ending war on the concept of time itself is enough to significantly impact the two teams that saw the age of their rosters change the most significantly from 2019.  An 11.2-year SWA drop is huge, and that was with a veteran like Cam Newton under center -- imagine the impact if they had gone after a rookie in last year's draft!  The Buccaneers saw their quarterback SWA shoot up by 17.5 years going from Jameis Winston to Brady, and bringing in veterans in Brady's orbit (hiya, Rob Gronkowski!) had an impact as well.

You can trace Philip Rivers' movement with the Chargers and Colts in third and fourth place, too. The Cowboys are here because of the departure of Jason Witten and significant changes along the offensive line (Terence Steele, Brandon Knight, and Connor McGovern all had 500-plus snaps at 23 years old), but the other four teams are all in this table due to a couple of quarterback moves. The travels of Brady and Rivers, more than anything else, upended this stat last season.

There are outliers every year, for sure—teams that suddenly see all their veterans leave due to salary cap constraints or what have you. But they normally clock in around where the Chargers finished, losing maybe a year of SWA as everything goes belly up. That happens, on average to 1.3 teams a year; that's the usual high. However, a change of 1.7 years—either a gain or a loss—is almost unheard of. The Patriots join the 2008 Chiefs as the only two teams to lose 1.5 years of SWA in a single season, and a -2.9 loss in offensive SWA is the biggest drop we have ever recorded.

Largest Drops in Offensive SWA, 2006-2020
Rk Year Team Year N-1
SWA
Year N
SWA
Diff Biggest
Loss
1 2020 NE 29.3 26.4 -2.9 Tom Brady (42)
2 2018 ARI 28.6 26.1 -2.5 Carson Palmer (38)
3 2008 KC 29.3 26.9 -2.4 Damon Huard (34)
4 2011 CIN 28.9 26.5 -2.4 Terrell Owens (37)
5 2009 PHI 28,3 26.0 -2.2 Jon Runyan (35)
6 2012 MIN 27.7 25.5 -2.2 Steve Hutchinson (34)
7 2011 DAL 28.7 26.6 -2.1 Jon Kitna (38)
8 2012 IND 27.9 25.9 -2.0 Jeff Saturday (36)
9 2014 JAX 26.6 24.7 -1.9 Brad Meester (36)
10 2011 SEA 27.8 25.8 -1.9 Matt Hasselbeck (35)

Quarterbacks are the driving force behind most of these drops—a change at quarterback is a decent enough proxy for the beginning of a rebuild, which is itself a decent proxy for an incoming youth movement. Carson Palmer's departures hit both the 2011 Bengals and 2018 Cardinals. The 2011 Seahawks said goodbye to Matt Hasselbeck. The 2012 Colts and 2014 Jaguars had highly-touted rookie passers—Andrew Luck and, er, Blake Bortles, respectively. But no single player has ever had as significant effect on the league's SWA as Tom Brady did in 2020. Maybe they can squeeze that one on to his Hall of Fame plaque.

Moving from the very old to the very young, we head down to Florida. The Jacksonville Jaguars were the youngest team in the league for the second year in a row, a feat only previously matched by the 2015-2016 Rams. The Jaguars the fourth-youngest team in our database, one year removed from being the eighth-youngest team—and, frankly, I wouldn't expect them to get any older anytime soon, as they continue to try to build some semblance of a functioning roster. They were very bad, but at least they were also very young, which puts them in a better situation than teams such as the Lions, Eagles or Jets, who were close to as bad with significantly older rosters. Jacksonville got the tanking portion of their rebuild done correctly, with plenty of young players getting experience that will hopefully come in handy when the team is actually competitive once again. The Jaguars had a league-high 11 players aged 25 or less rack up 500-plus snaps last season, and a couple of them actually looked like they might belong on a professional football team. Urban Meyer has his work cut out for him, but at least he doesn't have a lot of aging veterans to worry about.

While the Jaguars were the standout in overall SWA, three teams were among the 10 youngest we have ever recorded in offensive SWA: in descending order, the Broncos, Cowboys and Ravens. The Ravens, in particular, are worth noting—they were the only team in the top quarter of DVOA to have a snap-weighted age below 26.4; they're the one team in the NFL in the top quartiles of both being young and good. Mark Ingram led all Ravens 30-somethings in offensive snaps; he had just 160. Your grizzled veterans in the Baltimore offense were 29-year-old D.J. Fluker, 28-year-old Willie Snead, and 27-year-old Matt Skura, none of whom are under contract for 2021. Their oldest returning key offensive player was born in 1994. Before the season, the Ravens ranked first in our under-25 talent rankings, and even though their offensive DVOA dropped from 28.2% to 4.3% last year, there's still a very bright outlook for this offense in years to come, especially if they ever find a wide receiver.


2020 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).

2020 Snap-Weighted Age by Position
Team QB RB WR TE OL DL LB DB ST
ARI 23.1 25.0 28.0 25.8 28.1 27.1 26.7 26.7 31.7
ATL 35.0 25.4 25.5 28.6 27.6 27.0 25.7 25.6 26.8
BAL 23.4 24.3 24.7 26.4 25.2 28.9 25.5 26.2 33.7
BUF 24.3 24.6 26.9 26.4 27.3 27.2 25.2 27.0 24.2
CAR 27.7 25.9 25.2 26.1 28.0 24.9 25.8 25.2 26.8
CHI 28.3 23.8 26.1 27.5 26.8 28.0 27.4 27.2 30.0
CIN 25.2 26.3 26.1 24.8 25.4 26.7 25.6 26.0 33.4
CLE 25.1 24.8 25.9 24.0 26.3 27.7 25.6 26.8 27.0
DAL 30.1 23.9 24.0 25.4 25.1 27.5 26.3 25.2 33.4
DEN 24.3 25.6 23.8 24.4 26.3 27.0 26.1 26.6 27.4
DET 32.0 25.7 28.5 24.2 25.6 26.2 27.3 26.2 31.4
GB 36.8 25.3 26.1 27.7 27.8 25.3 25.7 24.6 29.4
HOU 25.0 26.6 26.5 29.4 26.6 26.7 26.9 25.4 30.3
IND 38.5 23.3 25.9 28.4 26.8 27.0 24.6 25.9 26.1
JAX 25.9 24.3 25.0 27.5 26.5 24.8 25.4 24.5 25.5
KC 25.7 23.5 25.5 28.2 28.4 25.6 25.6 26.1 26.5
LAC 22.6 24.1 25.0 26.3 26.4 26.5 24.3 26.6 26.0
LAR 25.9 24.0 26.2 26.4 27.2 27.4 25.4 25.2 29.4
LV 28.8 24.8 24.3 29.2 28.3 25.1 26.7 26.5 25.0
MIA 29.4 24.0 25.6 25.2 25.3 25.2 26.0 25.8 24.7
MIN 32.0 24.9 25.0 26.1 26.8 25.4 26.4 25.9 31.8
NE 30.6 26.8 26.8 24.0 26.2 26.9 24.6 28.3 26.8
NO 35.8 26.7 26.2 28.2 25.7 26.8 28.1 27.4 28.8
NYG 24.7 27.8 26.0 25.8 25.5 25.5 25.4 25.5 30.0
NYJ 26.0 28.2 26.2 26.4 26.9 25.5 26.6 26.1 25.2
PHI 26.3 24.3 24.9 27.4 27.4 28.2 25.1 26.5 27.0
PIT 37.0 23.6 23.5 28.1 28.1 28.9 26.0 25.8 29.0
SEA 32.0 25.1 24.8 27.4 27.9 26.5 28.1 25.3 27.1
SF 26.5 26.5 24.5 25.8 27.6 26.0 24.3 27.3 29.6
TB 42.5 25.1 25.5 29.3 26.1 29.2 27.0 24.0 28.4
TEN 31.9 25.7 24.6 26.0 28.9 26.6 25.9 26.9 33.6
WAS 28.7 25.3 24.7 27.9 27.4 24.3 27.0 24.9 31.0
AVG 29.1 25.2 25.5 26.7 26.9 26.6 26.0 26.0 28.7

No team quite managed the feat of being older or younger in every position group last season, though a couple came close. The Saints actually had a younger-than-average offensive line, thanks in large part to using their first draft picks in both 2019 and 2020 on Erik McCoy and Cesar Ruiz. Every Saints offensive lineman was under 30 last season, so that's at least one position group that won't be filing for social security next year.

Jacksonville just misses out on being younger everywhere thanks to their tight end; Tyler Eifert was the only Jaguars player in his 30s to play even 300 snaps last season. That clearly cannot stand, and the Jaguars declined his option for 2021. They're joined by the Chargers, where the duo of Casey Hayward and Chris Harris kept the Los Angeles secondary above average, and even that only barely scraped into the top 10.

And yes, Tom Brady can be seen clearly here, too. The Buccaneers were 13.4 years older at quarterback than the average NFL team; that's a record as well. One day, Brady will turn into a pumpkin and we can write these articles without referencing him. I mean, theoretically at least. There's a chance.


From: AgeWatcher@FootballOutsiders.com
To: GOAT@TB12.biz
Subject: Re: Re: Fountain of Youth location Florida?

Comments

11 comments, Last at 07 Apr 2021, 11:59am

1 Jets/Gase

Nice to see the Jets with the oldest average for running backs last year. Thanks Adam Gase

2 Am I misreading your chart?…

Am I misreading your chart?

It's not like New England's offense suddenly got young without Brady; they were still the fifth-oldest offense of the year last season, above average at every skill position.

Your chart seems to list the NE offense as 23rd in SWA. It's the team as a whole that was ranked 5th oldest. And they had the youngest TEs. Although I could understand not classifying that as a skill position for the Patriots last season.

3 The distributions are just as

Interesting as the averages and maybe more so.  Perhaps it has been done, but plotting the age curves for position would be interesting.  Can two "decay rates" fit most positions well?  Or do outlier positions with older stars like qb and OL display three?

5 The Packers finished with…

The Packers finished with the oldest offense and the second-youngest defense. Now I'm kinda curious - does a big offense/defense difference like that happen a lot? Is a SWA difference of 2.9 historically large or just a normal-sized yearly outlier?

9 It's not quite the largest…

It's not quite the largest we've seen, though it is up there.  The record goes to the 2006 Bears, who were 3.2 years older on offense than on defense; their oldest regular defensive starter was just 29 years old, and six starters (Tommie Harris, Tank Johnson, Charles Tillman, Nate Vasher, Chris Harris and Danieal Manning) were 25 or under.

The 2018 Saints also had a 2.9 year age gap, as did the 2014 Broncos, both of whom fall into the "aging legend quarterback" bucket along with the 2020 Packers.  It looks like the Packers actually do edge them out at 2.91 years, if you're looking to claim a victory here.

Is it a normally-sized yearly outlier?  Yes and no.  The average biggest difference since 2006 is 2.7, but that number has been dropping in recent years; three of the ten biggest gaps were all in 2006.  I wouldn't put TOO much weight on that fact; the average difference between offensive and defensive SWAs bounces around quite a bit.   Offenses have always been older than defenses, probably in small part due to quarterbacks playing into their late 30s more than most other positions, but there's no real notable trend to speak of there.  The gaps got a little smaller around 2012, and are back up to their historical averages today.

Basically, it's more a combination of "oo, neat!" and "man, Rodgers is getting old" as opposed to anything else.  Since 2016, the Packers have gone -1.0, -1.5, -1.8, -2.6 and now -2.9.

10 Honestly I think we're to…

Honestly I think we're to the point where you want 4 categories: QB, other offense, defense, and special teams. QB aging curves at this point are just far different from the rest of the offense.

11 Thanks much for looking! The…

Thanks much for looking!

The offense's age isn't just Rodgers - the TE group (mostly Marcedes Lewis) and o-lines are both pretty old too. I think I recall that the '18 Saints and '14 Broncos were similarly mostly veteran units outside of their old-man QBs.

It might also be interesting that the four teams here were all pretty good. Might just be a product of having old offenses and also good offenses (given how much offensive age is driven by the QB) being largely the same thing and also largely driving team success. What's also interesting is that, outside of the '20 Packers, those defenses were all pretty good!

6 Turnover.

With so much turnover week to week, game to game and year to year, not much can be gleaned from this type of analysis.

Skill determines playing time, regardless of age.  Brady is the perfect example (and outlier) for this.

Also, positional analysis would tell us more.  Different positions age differently due to the wear and tear.

RB's have a short shelf-life (except for Frank Gore) while WR's and DB's can play for years it seems.

7 Positional analysis

In reply to by DIVISION

Did you happen to look at the sortable chart? I mean, sometimes there isn't much to analyze. Kind of like the chart that shows the drastic age changes of offenses, which basically show that Brady went from NE to TB and Rivers went from LAC to IND.

Regarding the age drop overall in the NFL, while I am sure that fixed early wages make it more palatable financially to pivot to younger players, I wonder if there is also the "let them get experience" factor involved. Analytics have grown enough to show us that outside of QB, no one player truly affects a team by himself. (I'm not talking about how multiple injuries to the same unit, like KC's O-line, can have a cascading effect that does affect games.) So I can easily see coaches, GM's, and teams realizing that letting a younger player gain experience and perhaps grow into a above-average player is better than giving snaps to a veteran on the downside of his career. Obviously, there is value in competent play, and sometimes a veteran can deliver this better than throwing and untested rookie into the fire, so to speak. In other words, do you want a player whose floor and ceiling is established, or someone whose floor might be lower, but their ceiling is higher?

8 Positions like QB...

...demand excellence if you want the best chance to move forward.

Look at the ineptitude of the Bears, Jets and Jaguars for example.

When it comes to a transcendent player like Brady, age is merely a confounding variable.

I just hope we don't hear any more change of, "baby goat" this time next year, whether it's Mahomes, Mayfield, Jackson or even Lil' Kyler Murray.