Snap-Weighted Age: 2018 NFL Rosters

by Bryan Knowles

The modern NFL is a young man's game, but don't tell that to the champs.

We have been tracking snap-weighted age since 2012 -- calculating a team's metric not by just averaging the ages of the roster, but by weighting the age of each player by the number of snaps he played in the regular season. For the third straight year, we saw the league's SWA drop to a record low. We're now down to 26.45 years as the salary cap and rookie wage scale continue to incentivize teams to keep younger, cheaper players over pricey veterans.

However, for the fourth year in a row, the Lombardi trophy was hoisted by a team closer to getting their AARP cards than college diplomas. The New England Patriots have also set a new record; with a SWA of 27.9, they are the oldest team to win the Super Bowl since our records began.

To sum up, being young is in vogue, but experience wins championships, right? After all, each of the last five Super Bowl champs, and eight of the last 10, have been one of the ten oldest teams in the league by snap-weighted age. With the exception of the Legion of Boom Seahawks, we have never seen a team with an SWA below 26 even make the big game. So, teams should load up on those veterans in free agency and start planning their Super Bowl parade, yeah?

Well, no, of course, that's silly. The question about where a team wants to rank in SWA to be the most competitive remains open, and this year's results continue to muddy the waters. Half of the twelve playoff teams had an above-average SWA; half of them were below average. If you're looking for the One True Roster-Building Model, you'll have to keep looking elsewhere. Still, there's plenty to be learned from this year's numbers, so let's dive on in.

2018 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.

The level of correlation between SWA and DVOA is usually low, but 2018 takes the cake -- just a 0.04, which is far and away the lowest number we have ever seen. Last year, it was just 0.20, a number we thought was surprisingly low -- it had been hovering in the 0.30 range for years. But, at least in 2018, there was really no connection to how old or young a team was and how well they performed on the field. Age is just a number, indeed.

Offensive correlation was 0.29, bouncing back to historic norms, but defensive correlation was also essentially non-existent, at 0.01. That offensive number is within typical range, but defense usually shows at least a small correlation, with more experienced defenses generally having more success. In both cases, that has typically been a bit of survival bias -- older players are, in general, more effective than younger players, because bad players generally don't get second and third contracts -- but that was certainly not the case in 2018. The young Chargers, Cowboys, and Colts defenses compared fairly with aging units in Buffalo, Minnesota, and Denver. When the Rams won the NFC, we even saw our first Super Bowl team with an SWA out of the top ten since the 2014 Seahawks.

This may well be a one-year blip; there isn't an obvious rule change or roster construction issue that has come into play in the last year or two that would cause the correlation to drop so quickly. That being said, we did see a correlation drop between 2016 and 2017, though obviously not one this dramatic. Each of the last three years has also seen a new record set for number of games started by rookies, up to 1,175 in 2018 -- the first time we have ever had more than 10 percent of starts be made by first-year players. Perhaps we're on the front of a trend, albeit one that went to exaggerated lengths this season. With teams focusing more and more on rookies and other young players taking the load, we might see less variation in age ranges among teams, which would dampen SWA's ability to differentiate between clubs. Cost-controlled talent is probably the second-most important thing a team can have (after a franchise quarterback), and as more teams focus on collecting young players on below-market deals, we might see a homogenization of SWA.

On the other hand, it's possible this is just random variation -- with only 32 data points per season, it's not out of the realm of possibility that we have just noise here. Young teams could have just randomly performed better than usual in 2018, with a few outliers like the aging and struggling Raiders throwing standard correlation out of whack. Without an obvious source for the change, I'll stand on the side of "sometimes outliers happen" rather than "dramatic sea change" for now, but it's something we'll keep an eye on in years to come.

Despite the drop in correlation between age and success, the oldest team in the league raised the Lombardi Trophy. Tom Brady is old as dirt. There were six 40-year-old players in the NFL in 2018, but that includes four kickers and a long snapper who combined for 489 snaps all season long. Brady's a quarterback who put up nearly 1,100 offensive snaps! What Brady is managing to do at age 41 is nigh-unprecedented for a player at any position. Brady became the oldest non-specialist to receive a Pro Bowl invite, beating out Warren Moon's 1997 season by about three months. Yes, quarterbacks last longer than players at other positions (leading the league with an average SWA of 28.9), but no quarterback has ever lasted as long while playing as well as Brady has. Time's undefeated in the long run, but Brady's doing his best to take it the full 12 rounds.

Still, the Patriots' high SWA is not entirely due to Brady. Drop him, and the Patriots still finish second behind Carolina in the SWA order. New England had significant snaps from Devin and Jason McCourty (31 each), Patrick Chung (31), Chris Hogan (31), Marcus Cannon (30), and a slew of other players in their 30s. They had 8,909 snaps from the over-30 club, nearly 500 more than any other team. The Patriots having an older offense is nothing new; with the exception of 2015, they have ranked in the top five ever since 2012, and they once again had the oldest receiving corps in the league. The defense being old, however, is entirely new. Back when we started doing yearly articles on this, the Patriots routinely had one of the youngest defenses in the league. When they won the Super Bowl in 2014 and 2016, they ranked 19th and 14th in defensive SWA, respectively. They got old very quickly.

Part of that might be by design -- Brady's only going to have so many years left in him, so why not try to maximize your window by trading for someone like Jason McCourty? Part of that, however, is due to the draft. New England has not been very successful at finding defensive standouts in the draft in recent years, with only four picks from the last five seasons getting any starts for the Pats on defense in 2018. That isn't sustainable for success in the long run, and is typically the end state for any dynasty: a lack of good, young talent to replace aging and fading stars. I'm sure New England's AFC East rivals are pleased as punch, then, that the Patriots have the most picks in the upcoming draft, picking six times in the first 101 selections.

The Panthers nearly set a record of their own, with the oldest defense since the 2012 season, a full 1.3 years older than any other comer. Mike Adams (37) soaking up 938 defensive snaps is the prime culprit here, but Thomas Davis (35), Julius Peppers (38), Mario Addison (31), and Captain Munnerlyn (30) all added at least 500 snaps to Carolina's total. Peppers, especially, being able to contribute so much at age 38 is an incredible capstone to his Hall of Fame career. He retired this offseason, while Davis has moved on to the Chargers and both Munnerlyn and Adams remain unsigned as the market for 38-year-old safeties coming off of down seasons isn't as robust as one might hope. Considering Carolina fell from seventh to 22nd in defensive DVOA a year ago, a youth movement makes a lot of sense for the Panthers; being old and bad doesn't do anyone any favors.

You'd rather be young and good, and both the youngest offense and defense ended up making the playoffs in 2018. Both Houston and Dallas boasted very young offenses, separated by less than 0.2 years in SWA. Obviously both teams still have a quarterback on a rookie deal, which matters a lot, but they also each had five primary offensive linemen aged 28 or younger, as did third-youngest Cleveland. Because offensive linemen generally don't swap in and out, having young linemen is the fastest way to a low offensive SWA. Young and good don't always go hand in hand -- Houston's young linemen ranked 32nd in pass protection and 27th in adjusted line yards. Free agent acquisition Matt Kalil is probably not the answer (or, at least, not to any question Houston wants to ponder), but the idea of adding a veteran presence to the line doesn't seem like a bad instinct here.

At least Houston had an experienced defense to along with their young offense. Dallas was one of two teams with less than 500 snaps from players in their 30s, along with the Browns. Of the two teams, it feels like the Browns are better set up for long-term success. Not only did they have a higher DVOA last season, but the majority of their young players will all still be on their rookie deals for a while. They'll have a few more years to grow together before their initial contracts expire, meaning that they'll not only hopefully keep improving, but will allow plenty of cap room for adding veterans like Sheldon Richardson and Oliver Vernon.

The Cowboys, on the other hand, are beginning to run out of time. Dak Prescott, La'El Collins, Tyron Smith, Anthony Brown, Maliek Collins, and Amari Cooper are all on their last years of their deals, and Ezekiel Elliott's fifth-year option is coming up shortly, as well. All were 25 or younger and played at least 500 snaps for the Cowboys last season. Being young and cheap is great, but you have to take advantage of that situation while it lasts, because it seems unlikely that Dallas will be able to afford second contracts for all of their major contributors. That makes their 2019 window more of a "now or never" sort of situation, at least for this incarnation of the Cowboys.

2018 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).

Cleveland was the only team in the league to have a younger-than-average roster at every positional group, just squeaking in under the wire in the defensive backfield. Again, this a reason for optimism going forward -- the team already took a huge step between even the beginning and end of 2018, and the vast majority of their roster is both young and under contract control for a few more seasons. Dallas and Cincinnati nearly join them, with only their special teams units keeping them from hitting the under. It's only 37-year-old L.P. Ladouceur that keeps the Cowboys from completing the sweep, and I don't believe the age of your long snapper typically has a massive effect on a team's performance.

No team was older than average at every position, though three came close. The Patriots were about a year younger on both the offensive and defensive lines; it's once you get out of the trenches that the greybeards start showing. Washington was older at every single offensive position, but they also had the youngest defensive line in the game, with just 22.9 SWA. Their top four defensive linemen all were age 24 or younger, and their only player 30 years or older, Ziggy Hood, was released in October. Arizona was only younger than average at offensive line, where injuries decimated any player with even the slightest bit of experience, and quarterback, where first-round pick Josh Rosen spent most of his rookie season running away thanks to that inexperienced offensive line.