(Wilfredo Lee/AP Photo)
One of the few constants throughout each professional sports league is the absence of consistency. NBA teams used to play through the post, but now they hunt for three-pointers with a significantly more spaced-out offense. In MLB, bunting with a runner on and no outs used to be inevitable, but the occurrence of this event has been dwindling for years. In the NFL, establishing the run used to be paramount to having a productive offense, but a prolific passing attack has become the primary concern. The metamorphoses of these sports all have two things in common: they have been met with forceful opposition and they were driven by an analytics revolution.
"Running backs don’t matter" is a phrase that has been uttered countless times among the NFL analytics community partly in jest but also to summarize the increasingly growing belief that running success is not a result of a talented runner. Instead, the amount of yards gained on a run is mostly determined by offensive line success, personnel, and field position. According to FiveThirtyEight, who looked at 10 years’ worth of data from ESPN’s Sports & Information Group, "96 percent of yards-per-carry totals are explained by the offense’s field position and the number of men the opponent has in the box."
(FiveThirtyEight)
Team success is also a determinant of running success. Good teams tend to have good offensive lines. Using Football Outsiders’ adjusted line yards to evaluate offensive line play, one of the hardest aspects of football to quantify, seven of the top ten offensive lines were on playoff teams (Dallas, Oakland, and Cleveland are the three non-playoff teams).
There is a similar trend when examining the most efficient runners in the league last year. The graph below illustrates running back efficiency from 2019. The statistic on the y-axis is EPA (I use EPA per play, click here for more information on EPA), which is mainly how I will evaluate running backs. The traditional running back statistics, such as yards gained, can be flawed because they are mainly determined by volume (number of rushing attempts).
The graph is a little difficult to read because there are a lot of labels — it includes the 46 running backs that had at least 94 rushing attempts last year (so that it includes David Johnson) — but there are still some conclusions that can be made from it.
The first thing that stands out is the running backs that have separated themselves from the rest of the pack: Mark Ingram, Gus Edwards, Raheem Mostert, and Kenyan Drake. The two most efficient running backs were on the same team, and this graph cut off Lamar Jackson because he was too good, which would make the three most efficient runners coming from the same team. Mostert, the third most efficient running back in the league, went undrafted and had been signed and released by six teams before finding his way to the Niners and Kyle Shanahan, a coach who is known for scheming an incredibly efficient running game wherever he is coaching. Looking at the top three in EPA among running backs, it's clear that running success is team dependent.
The same is true if you extend the picture beyond the top three. Seven of the top ten and 11 of the top 15 in EPA made the playoffs last season. Similarly, eight of the bottom ten in EPA missed the playoffs (Frank Gore and Alexander Mattison are the two that made the playoffs). There are also two pairs of running backs in the top 15 in EPA from the same team: Baltimore’s Ingram and Edwards and Green Bay’s Aaron Jones and Jamaal Williams.
Going back to the "Running Back Efficiency" graph, most of the running backs are grouped with only .05 EPA separating them. Also, the only running backs with a positive EPA per play last season were Ingram, Edwards, Mostert, Drake, and Dalvin Cook. This shows that 1) most running backs provide similar value, and 2) that value tends to be negative.
These points, along with the short shelflife of running backs, are the main reasons why nerds like me say that "running backs don’t matter." They are easily replaceable and the success of a team’s running game is not determined by their skill or their contract. Because of this, teams should not spend substantial capital, high draft picks or salary cap, on running backs.
This is easy to comprehend if you look at the highest-paid running backs last season. The highest-paid running back last season was Ezekiel Elliot, who was 11th in EPA. The next highest-paid was Todd Gurley, who was 31st in EPA, followed by Le’Veon Bell who was 43rd in EPA, which was the fourth-lowest among the 46 running backs in the sample. The fourth highest-paid back was David Johnson, who was 40th in EPA and lost his starting job to Kenyan Drake, who I mentioned before had the fourth-highest EPA even on a bad team with a mediocre (at best) offensive line. The fifth highest-paid player was Devonta Freeman, who was last in EPA before being cut by the Falcons and remains unsigned.
Some of these backs suffered injuries that have hindered their success, but that is part of the problem with paying running backs. According to Statista, the average career length of a running back is only 2.57 years, the lowest mark for any position. Most running backs do not provide any value beyond their rookie contract.
Because backs have such short periods of value and running success is determined by offensive line, field position, and personnel, it’s disadvantageous to pay running backs at the expense of other, more valuable, positions. However, teams still hand out increasingly large contracts to running backs because that is what teams have been doing since the beginning of football, and running backs tend to be fan-favorites. Imagine if the Panthers didn’t pay Christian McCaffrey and let him walk to another team. They may get heat for not extending perhaps the best running back in the league, but they also wouldn’t be stuck with an enormously overpaid running back. Not every team will be able to trade their overpaid running back to Bill O’Brien for one of the best wide receivers in the league. Most will be stuck with a huge cap hit at running back and holes at several other positions.
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