In each of the last two years , I’ve presented the AV-adjusted age of each roster in the NFL. Measuring team age in the NFL is tricky. You don’t want to calculate the average age of a 53-man roster and call that the “team age” because the age of a team’s starters is much more relevant than the age of a team’s reserves. The average age of a team’s starting lineup isn’t perfect, either. The age of the quarterback and key offensive and defensive players should count for more than the age of a less relevant starter. Ideally, you want to calculate a team’s average age by placing greater weight on the team’s most relevant players.

My solution has been to use the Approximate Value numbers from Pro-Football-Reference.com. The table below shows the average age of each team, along with its average AV-adjusted age of the offense and defense. Here’s how to read the Rams’ line. In 2013, St. Louis was the youngest team in the league, with an AV-adjusted team age of 25.5 years (all ages are measured as of September 1, 2013). The average AV-adjusted age of the offense was 25.9 years, giving the Rams the third youngest offense in the NFL. The average age of the defense was 25.2 years, and that was the youngest of any defense in football in 2013.

Rk Team Ovr Age Off Age Off Rk Def Age Def Rk 1 STL 25.5 25.9 3 25.2 1 2 SEA 26 25.5 1 26.4 10 3 CLE 26.1 26.6 10 25.7 3 4 TAM 26.3 27.2 19 25.2 2 5 NYJ 26.5 26.4 7 26.6 14 6 KAN 26.5 26.3 6 26.6 15 7 GNB 26.6 26.1 5 27.1 19 8 DAL 26.6 26.6 11 26.6 16 9 CIN 26.7 26 4 27.1 21 10 BUF 26.7 27 15 26.5 13 11 JAX 26.7 26.9 14 26.5 12 12 TEN 26.8 27.5 21 25.9 4 13 HOU 27 27.6 23 26.1 8 14 PHI 27.1 27.7 24 25.9 5 15 NWE 27.1 28.1 28 26 7 16 SDG 27.2 27.8 25 25.9 6 17 MIN 27.2 27 16 27.7 25 18 MIA 27.3 26.6 9 27.7 23 19 DET 27.3 27.2 18 27.1 20 20 CAR 27.3 28.5 31 26.5 11 21 BAL 27.4 26.8 12 27.7 24 22 IND 27.4 25.7 2 28.6 32 23 OAK 27.4 27.1 17 27.6 22 24 WAS 27.5 26.4 8 28.3 31 25 PIT 27.6 26.8 13 28.2 30 26 CHI 27.6 27.4 20 27.7 26 27 DEN 27.7 28.2 29 26.8 17 28 ATL 27.7 28 26 27.1 18 29 NOR 27.7 29 32 26.2 9 30 NYG 27.8 27.5 22 27.7 27 31 SFO 28.3 28.4 30 27.9 28 32 ARI 28.3 28 27 28.2 29

With Seattle and San Francisco meeting in the NFC Championship game, it’s easy to categorize the best division in football as the Seahawks and 49ers battling for conference supremacy and the Rams and Cardinals fighting for the leftover scraps. And that has been undoubtedly true the last couple of years. But when it comes to age, St. Louis and Seattle are the two youngest teams in the league, while San Francisco and Arizona are the two oldest.

The Rams are absurdly young on defense, and the RG3 trade has positioned the team for long-term success. Robert Quinn (23.3 years old on 9/1/2013), Michael Brockers (22.7), Alec Ogletree (21.9), and Janoris Jenkins (24.8) were all under the age of 25 at the start of the 2013 season, leaving Chris Long to clock in at an “old” 28.4 years. Kendall Langford (27.6) is the only other Rams defender with an AV of more than 5 that is older than 25. The offense isn’t much older. Of the 15 offensive players with at least 3 points of AV, only three — center Scott Wells, guard Harvey Dahl, and backup quarterback Kellen Clemens — are over 30. Only two more — tackles Jake Long and Chris Williams — were over 28 last year. Ignoring Clemens, that means 10 of the Rams’ 14 key offensive players were 26 or younger at the start of last season. The youngest five of those were all skill position players — Zac Stacy (22.4), Tavon Austin (22.5), Daryl Richardson (23.4), Chris Givens (23.7), and Brian Quick (24.2). Quarterback Sam Bradford (25.8) is quickly becoming the old man of the group, relatively speaking. Could the Rams be the breakout team of 2014? In any other division, I’d be optimistic about making that statement, but St. Louis appears well-positioned for the next three-to-five years.

Seattle is full of young players, which is not surprising because the Seahawks were the youngest team in the NFL in 2012. This year, Seattle had the youngest offense in the NFL, and all of that unit’s contributors were under the age of 28. Russell Wilson (24.8), Marshawn Lynch (27.4), Max Unger (27.4), Golden Tate (25.1), Doug Baldwin (24.9), and J.R. Sweezy (24.4) form a young core that should compete for years. The only long-term questions for the offense are figuring out how to keep Percy Harvin healthy (he doesn’t turn 26 until May) and making sure that Robert Turbin (23.7) or Christine Michael (22.8) can handle the load when Lynch declines. As Doug Farrar notes, Seattle is the second youngest Super Bowl team ever, and positioned to make 2013 the start of a dynasty.

San Francisco, on the other hand, is a very interesting team to watch. It was only a year ago that I thought the 49ers could be the Lombardi Packers. And it’s hard to get too down on a 49ers team that has made it to the NFC Championship Game in three consecutive seasons. With Colin Kaepernick around, one would think the window would be open for a long time. And it might be, but only if San Francisco can restock on both sides of the ball.

Outside of Kaepernick, the four most important players on offense in 2013 were Anquan Boldin (32.9), Joe Staley (29.0), Frank Gore (30.3), and Vernon Davis (29.6). In theory, Michael Crabtree (26.0) and Marcus Lattimore could keep the gravy train rolling at wide receiver and running back, but (1) the 49ers still need a second receiver (and Boldin is a free agent) and (2) Lattimore is no sure thing to carry Gore’s torch. Spending high draft picks on A.J. Jenkins and LaMichael James have hurt, and that track record doesn’t exactly inspire much hope in Vance McDonald replacing Davis down the line, either.

On defense, Justin Smith (33.9), Ahmad Brooks (29.5), Patrick Willis (28.6), Carlos Rogers (32.2) and Ray McDonald (28.9) contribute to the one of the five oldest defenses in the league. And while age isn’t an issue for NaVorro Bowman (25.4), his 2014 prognosis is cloudy after suffering a devastating knee injury in the NFC title game. Against that backdrop, hitting on multiple picks out of the 2013 class of Eric Reid, Cornellius Carradine, Corey Lemonier and Quinton Dial is a key to keeping the defense among the elite in the NFL.

You might not have guessed that Arizona was the oldest team in the NFL, but other than Patrick Peterson (23.1) and Michael Floyd (23.8), the top Cardinals were all in their late 20s or 30s in 2013. That includes Karlos Dansby (31.8), Carson Palmer (33.7), John Abraham (35.3), Eric Winston (29.8), Calais Campbell (27.0), Darnell Dockett (32.3), and Larry Fitzgerald (30.0). We were all impressed with the job Bruce Arians did in his first season as head coach, but Arizona’s long-term prognosis may be the least inspiring of any team in the division.

Windows of Opportunity

The Colts have the youngest offense in the AFC but the oldest defense in football. Robert Mathis alone makes up about 15% of the team’s defensive AV, and he was 32.5 in 2013. Add in Cory Redding (32.8), Antoine Bethea (29.1), and Erik Walden (28.0), and it’s hard to paint a pretty picture for the long-term success of the defense. Even second-year player Jerrell Freeman (27.3) isn’t very young after spending three years in Canada.

That means the Andrew Luck (24.0) Colts may end up looking a lot like the Peyton Manning Colts for the next few years. The offense is loaded, even once Reggie Wayne (34.8) moves on. T.Y. Hilton (23.8), Anthony Castonzo (25.1), Coby Fleener (24.9), and Trent Richardson (22.1) provide a young nucleaus for Luck, and that doesn’t even include potential contributions from players like Dwayne Allen (23.5) and Da’Rick Rogers (22.2), who added little in 2013.

Meanwhile, the Saints are an aging offense that has probably seen its best days. Drew Brees (34.6), Jahri Evans (30.0), Ben Grubbs (29.5), Marques Colston (30.2), Darren Sproles (30.2), and Zach Strief (29.9) give New Orleans the oldest offense in the league. Jimmy Graham (26.8), Kenny Stills (21.4), and Nick Toon (24.8) inject the offense with some youth, but it’s fair to wonder if the window of opportunity has closed on the cap-strapped Saints making another run.

Staying in the NFC South, because of Cam Newton, it’s easy to think of Carolina as a young offense. But Steve Smith (34.3), Jordan Gross (33.1) and Travelle Wharton (32.3) are on the wrong side of the age curve, while Greg Olsen, Ryan Kalil and Ted Ginn all turn 29 in March or April. The Panthers had the second-oldest offense in the league, and will need to make some upgrades at wide receiver and on the offensive line in the offseason.

New England’s a team that you might think of as old, but that’s only the case on offense. Tom Brady (36.1) and Logan Mankins (31.5) are the best players on that side of the ball, and Daniel Connolly turned 30 on September 2nd. Even some of the “young” guys aren’t that young — Julian Edelman (27.3), Danny Amendola (27.8), Kenbrell Thompkins (25.1), LeGarrette Blount (26.7) and Sebastian Vollmer (29.1) are all over twenty-five. Shane Vereen, Stevan Ridley, and Rob Gronkowski all turn 25 before June, too. The average age of the Patriots starting five offensive linemen was 28.9, and it will be interesting to see how that line holds up — and how younger players are integrated — following the retirement of line coach Dante Scarnecchia.

On defense, New England is very young, although two of its best players – Aqib Talib (27.5) and Rob Ninkovich (29.6) – are two of the oldest. But the defense can build around Devin McCourty (26.1), Chandler Jones (23.5), Dont’a Hightower (23.5), Brandon Spikes (26.0), Chris Jones (23.1), Jamie Collins (23.3), and Alfonzo Dennard (24.0). Because of injuries, Jerod Mayo (27.5) and Vince Wilfork (the oldest 31.8 year old ever) don’t bring the average age up, although that will change next year (at least, Pats fans hope as much).

As for the Broncos? The offense’s age is weighed down by Manning, of course, so it’s hard to get much of a read on the team. In a situation like this, the goal just needs to be to hit on your draft classes. The Broncos added Von Miller, Rahim Moore, Orlando Franklin, and Julius Thomas in 2011, although the 2012 class has been less productive (Derek Wolfe, Brock Osweiler, Ronnie Hillman, and Danny Trevathan). This year’s class has been somewhat of a dud — Sylvester Williams, Montee Ball, Kayvon Webster — although this may be a case where it’s just difficult for rookies to integrate the lineup of a Super Bowl team. For Seattle, only Michael Bowie (8 starts at tackle) and Luke Willson (7 starts at tight end) have made much of a contribution among the Seahawks rookie class.