It is difficult to quantify the average salary of second-string NFL running backs. This is due in part to the fluid nature of depth charts at this position and the penchant for modern NFL teams to go with two-back tandems resulting in a lack of true first-string running backs across the league.

NFL Running Back Salary

As of 2009, the average salary for all running backs in the NFL, including second-string running backs, was $957,360 according to Sports Illustrated. This average salary is not as high when compared to the average salary for other skill positions, such as quarterback and defensive end. Running backs also have a short lifespan in the NFL with an average career length of 2.6 years. The heavy physical contact a running back receives is to blame for the shorter career length. This is shorter than the average career span of 3.5 years for all NFL position players.

Two-Back Tandems

As of 2010, the notion of first- and second-string running backs in the NFL is disappearing. Teams are responding to the wear and tear placed on first-string running backs by using running back rotations with two and sometimes three backs. This is causing a shift in salary demand for the position as second-string backs can point to an increase in playing time as a reason for a higher salary. For example, in 2009 running back Chester Taylor signed a four-year, $12 million contract with the Chicago Bears to be the second-string running back to starter Matt Forte. This contract was only $2 million less than the four-year deal Taylor signed in 2006 to the be the starting running back for the Minnesota Vikings.

On-Field Production

The performance of a running back dictates playing time. The better a back performs on the field, the more playing time he gets. It's not uncommon for a second-string running back to eclipse a starting back over the course of a season. This turns the higher paid starter into the second-string reserve. This occurred during the 2010 season when New York Giants starting back Brandon Jacobs lost his job to second-string running back Ahmad Bradshaw. Jacobs earned $3.5 million during that season while Bradshaw earned far less at $460,000.

Paying for Reputation

The life of an NFL running back rarely lasts past 30 years old. Only a handful of backs, including Walter Payton, remained productive after turning 30. An older running back may sign with a new team as the second-string back but receive a salary that is commensurate with his reputation on the field and ability to draw fans. This occurred in 2010, when former Chargers running back and former NFL MVP LaDainian Tomlinson signed a two-year, $5.1 million contract with the Jets. Tomlinson participated in a two-back tandem with Shonn Greene during the 2010 season.