Here's how the averages shake out:
2013 AV-Adjusted Team Age — FootballPerspective.com
Overall AVG Age 27.3 NFL Rank: 20
Offense AVG Age: 28.5 NFL Rank: 31
Defense AVG Age: 26.5 NFL Rank: 11
I was surprised that a 2 year average age difference between offense and defense would make that much of a difference in the rankings. My first thought was the offense is being skewed by the graybeards Jordan Gross (33) and Steve Smith (34). But when I look at the roster I see more 30+ year old defenders that I expected so I'm wondering maybe they only looked at starters.
Players over 30 or older:
Steve Smith (34)
Jordan Gross (33)
Ben Hartsock (33)
Travelle Wharton (32)
Geoff Hangartner (31)
DeAngelo Williams (30)
Derek Anderson (30)
Colin Cole (33)
Drayton Florence (33)
Quinton Mickell (33)
Dwan Edwards (32)
Chase Blackburn (30)
Thomas Davis (30)
The author actually doesn't average just starters or the entire roster but instead has a calculation that weights the starters but also includes the whole roster.
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.
So in summary though the offense is one of the oldest in the league and I hope it stays that way as I want the majority of the graybeards to come back. The defense on the other could get a lot younger very quickly given the four oldest guys may not be back.