The Running Back Cliff

When imagining the perfect running back for your fantasy team, there are a lot of factors to take into account. Things like coaching scheme and usage contribute to who can be a top performer.

Another indicator is age. It is practically a dirty word to name a running back as 30 years old, but with as much as the game and especially that position has changed in terms of specialization and workloads, I wanted to challenge the idea of the 30-year-old decline with some specific research. To do so, I took the top 24 running backs—which is the number of starters in a typical 12-team league—from the last six seasons based on standard scoring. I then tagged those productive player seasons with the ages of the backs as of the beginning of each season.

Rather than limit my results to an average age, I also identified the range of common ages during that span and took it a step further with standard deviation to see how varied those averages were from year to year. Here are those results:

It was not a huge surprise to find that the average age of fantasy's best running backs is 25.6 years old. And looking separately at each of the past six seasons, there has not been much variance in the average age of the top backs. At its youngest, that average was 24.9 years. At its oldest, it was 26.0 years.

What was more surprising was just how stark the decline in frequency of productive running back seasons was at 29 years old, even earlier than the axiom of the 30-year-old back would suggest:

The top fantasy backs are pretty evenly split among backs just beginning their careers at 21 and 22 years old and each subsequent age through 28. There is a peak around age 26, which is close to the overall average age from the period, but the overall trend more closely follows a plateau. However, the frequency of productive fantasy seasons for backs declines abruptly at age 29. In all, 90 percent of fantasy’s top running backs are 28 years old or younger.

For fantasy purposes, that trend suggests you’d be wise to stick with running backs in that 21-to-28-year-old range. Interestingly, the 2015 season will feature several elite backs entering their age-29 seasons, including Matt Forte, Marshawn Lynch and Arian Foster. It can be difficult to trade away a player who has been such a productive centerpiece to your dynasty team, but a dynasty owner who wants to remain successful over the long term must make decisions before they become obvious ones to every player. History tell us that now is the time to try to trade those formerly elite backs.

Michael Moore is a contributor to the Dynasty section of Pro Football Focus. Check out his dynasty-centric website at www.DynastyFantasyFootballCentral.com or follow him on Twitter @Dynasty_FFC.