Some teams, like the Rams have done a good job of fielding a very young roster; others, like the Raiders, have made a conscious effort to head in the other direction. Overall, the Rams are more representative of the current trend. NFL teams have made a shift towards younger players in the last three years, although you might be surprised by just how dramatic and sudden the change has been. The drop in Approximate Value (AV)-weighted ages of NFL rosters in the last three years is more than 50% larger than in any other three-year period in NFL history.

Looking at the graph, there are two seismic shifts that changed the age distribution of the NFL in the Super Bowl era: the increase that started in the late ‘80s and the decrease in the last five years. These changes tell us about how changes in the collective bargaining agreement can change the NFL landscape in both subtle and dramatic ways.

First, the increase in NFL roster age in the 1980s coincides pretty closely with the introduction of Plan B free agency in 1989. It looks like the increase maybe starts a year too early. Remember, though, that the 1987 age may be skewed a bit by the three games with replacement players. Taking that point in mind, the increase from 1988 through 1993 coincides exactly with the introduction of limited free agency.

Given how little freedom Plan B actually gave to players, it may be surprising that Plan B had much impact on NFL roster age. However, Plan B did more than just make it possible for players such as Everson Walls to switch teams; it made their careers longer.

The graph above―which shows the average career length for players who played their last season that year and played at least three years―shows an increase in career length about five years after free agency started. ^[1]The graph bounces around in the earlier years and even a fair bit more recently, so I took a moving average of the year and the one immediately before and after. Due to the moving average, one thing … Continue reading We’d expect free agency’s impact to take a little while to show up in this graph, just as it does.

Free agency thus appears to have perhaps extended average career lengths by about half a year. Before free agency, players like Walls would have retired without the ability to find the team that needed their skills. Plan B allowed teams to protect 37 players, giving freedom of movement to everyone else. The players who benefited from that system were exactly those whose original team no longer saw them as essential, who could more easily find a new team. Other explanations for the change are possible, such as better conditioning or nutrition, but the move to longer careers lines up pretty closely with the free agency explanation that I think that’s probably it, particularly in light of what the data seem to say about the current CBA.

In contrast to the career-lengthening impact of free agency, the current CBA seems is likely to lead to shorter careers. Players on cheap rookie contracts can fulfill roles that used to be carried out by veterans, causing those players to retire. This trend is suggested by the move towards younger rosters in the first figure. While it’s too early to see this trend in the ages of players who have retired, we can look instead at the chance that a player has left the league.

This graph shows the chance that a player who is at least 33 years old and provided at least 5 points of AV does not play the following year. Notice the big increase in 2012. Since 1980, good players in their mid-30s were never more likely to retire than they were in 2012. We’ll see if the trend continues, but the overall pattern of teams valuing older players less fits with the other data. So I expect it’s likely to keep going this way, the Oakland Raiders defense notwithstanding. ^[2]I spent some time trying to predict how likely it is that the Raiders defense will have an AV-adjusted age of over 30 this year, and I think it’s possible if Khalil Mack starts off more slowly than … Continue reading