As a result, quarterbacks are more integral to winning than either running backs or wide receivers. Below shows how much. Each position player is ranked according to his 2104 win probability added, which simply measures the impact of each play toward winning and losing. As you can see, the top five quarterbacks per this metric vastly outweigh their comparables at running backs and wide receiver and continue to do so for the top 15 at the position. It’s not even close.
Perhaps this explains the larger-than-expected number of teams interested in signing Brian Hoyer as their quarterback. It also explains why running backs have such a short shelf life, one that is getting shorter with each passing year. Below is the average tenure of running backs, quarterbacks and wide receivers in the year they were no longer active. The dotted lines are five-year moving averages to help smooth out the curves. As you can see, passers (and with them, receivers) are on the rise while rushers are on the decline. From 2010 to 2014, the average tenure of a running back no longer in the league was 5.2 years, compared with 7.2 for quarterbacks and 6.4 for receivers. That’s almost a year difference from the period encompassing 2001 to 2005.
Running backs that averaged over 10 AV per 16 games and ended their career between 2010 and 2014 played 9.5 seasons, on average. That same class of rushers who stopped playing between 1995 and 1999 played an average of 13 seasons.
But this isn’t happening “less frequently and less abruptly to top quarterbacks and standout wide receivers.” In fact, quarterbacks who average more than 10 AV per 16 games over their career have a life span close to rushers of the same caliber. But wide receivers of this ilk have seen their time on the field increase over the past five years.
In other words, game-changing receivers are in the league two more years than they were in the previous five-year period and three years more than star passers and rushers.
This is part of the reason why it is risky to sign a star running back like LeSean McCoy but sound strategy by the Packers for locking up receiver Randall Cobb.
At some point running backs will actually become undervalued and a team will use Moneyball-esque strategies to gain a significant edge on their competition. But for now, don’t run out and buy a jersey if your team signs that prized free agent running back.