Where Were the Biggest Production Gaps For Running Back Duos in 2015?
Running backs don’t carry the ball like they used to. The idea of the bellcow back has diminished in today’s game, and there’s been a clear rise in a running-back-by-committee approach. There’s no inherent advantage in either approach, as Joe Redemann pointed out. The teams that ride running backs for a significant majority of their carries usually have a back that can handle that type of responsibility. Those that don’t split it up.
But not all running-back committees are created equally, and just splitting carries doesn’t mean the backs are equal in production. Using our Net Expected Points (NEP) metric, we can take a look at how production differed in each backfield that went with a heavy running-back-by-committee approach. For those new to NEP, it measures the expected points each team adds to its total for the drive on each play throughout the season relative to historical expectations.
There are plenty of ways to determine what qualifies as a committee, but we’re not going to get into all committees here. For this exercise, we’re going to look at teams that had at least two running backs carry the ball 100 times during the 2015 season.
This gives us a group of teams and running backs that shared a high percentage of carries. Some of these splits were due to injury -- like the Pittsburgh Steelers, for instance -- but we can still look at backs who shared time and still carried the ball quite a bit during the season. In 2015, there were 12 teams that had at least two running backs carry the ball at least 100 times. They’re listed in the table below along with the Rushing NEP per carry (abbreviated to RNEP/P) of each back and the difference in Rushing NEP per carry difference between the two. Just because some of these individual values are negative doesn’t mean the majority of these players were bad. The average Rushing NEP per carry among all 44 running backs with at least 100 carries last season was -0.03.
| Team | RB | Carries | RNEP/P | RB | Carries | RNEP/P | Difference |
|---|---|---|---|---|---|---|---|
| ARI | David Johnson | 125 | 0.15 | Chris Johnson | 196 | -0.07 | 0.22 |
| BAL | Justin Forsett | 151 | -0.02 | Buck Allen | 138 | -0.16 | 0.14 |
| SEA | Thomas Rawls | 147 | 0.08 | Marshawn Lynch | 111 | -0.05 | 0.13 |
| WAS | Alfred Morris | 202 | -0.08 | Matt Jones | 144 | -0.18 | 0.1 |
| CIN | Gio Bernard | 154 | 0.02 | Jeremy Hill | 223 | -0.06 | 0.08 |
| PIT | DeAngelo Williams | 200 | 0.07 | Le'Veon Bell | 113 | 0.03 | 0.04 |
| PHI | Ryan Mathews | 108 | 0.00 | DeMarco Murray | 194 | -0.03 | 0.03 |
| CLE | Isaiah Crowell | 185 | -0.06 | Duke Johnson | 104 | -0.09 | 0.03 |
| GB | Eddie Lacy | 187 | -0.06 | James Starks | 148 | -0.08 | 0.02 |
| CHI | Jeremy Langford | 148 | 0.01 | Matt Forte | 218 | 0.00 | 0.01 |
| TB | Doug Martin | 288 | -0.01 | Charles Sims | 107 | -0.01 | 0 |
| DEN | Ronnie Hillman | 207 | -0.05 | C.J. Anderson | 152 | -0.05 | 0 |
There was no bigger difference in production than between the Johnsons with the Arizona Cardinals. Chris Johnson was brought in to be the veteran presence and got the lion’s share of the carries at the start of the season. But then David Johnson started to emerge as the better back and took the reigns throughout the playoffs, mostly due to an injury suffered by the elder Johnson.
David Johnson’s now projected by most to be the lead back for the Cardinals heading into 2016. He was the most efficient runner in the league with at least 100 carries at 0.15 Rushing NEP per carry. The difference in rushing efficiency between the rookie and veteran was significantly more than the total of the best back in the league on a per-carry basis, illustrating Chris Johnson's struggles as the lead man.
Also of note, this difference in production is just measured on the ground and doesn’t factor in the passing game. Well, David Johnson was quite good there, too, ranking second among all running backs in Reception NEP per target with 32 more targets than the lone player ahead of him.
The second biggest gap may come as a surprise, between Justin Forsett and Javorius Allen with the Baltimore Ravens. Forsett was just an above-average runner for the Ravens before injuries cut his season short. The younger Allen eventually took over as the lead back but was one of the worst runners on a per carry basis (only Melvin Gordon and Matt Jones were worse with at least 100 carries). But with Forsett entering his age-31 season, Allen could be in line to take over the starting role, though he’ll also have to beat out rookie Kenneth Dixon.
Washington’s Matt Jones is another in line to take over as the starter for his team after being the worst member of a duo in 2015. By Rushing NEP per attempt, no back was worse with at least 100 carries. Jones, though, will have little competition for the job with Alfred Morris now in Dallas after departing as a free agent. If there’s a silver lining for Jones and Washington, he was the only back better than David Johnson in Reception NEP per target, though that came on just 25 targets and 19 receptions.
One other pairing of note comes from the Cincinnati Bengals with Giovani Bernard and Jeremy Hill. Last season, Hill continued to get the starts and the bulk of the carries in the run game despite being outperformed by Bernard on a per-attempt basis. Including the playoffs, Hill out-carried Bernard in 12 of Cincinnati’s 17 games with Bernard getting fewer than 10 carries in 10 games, though one of those games saw Bernard out-carry Hill, eight to seven. Bernard, of course, was a much bigger factor in the passing game with 66 targets on the season compared to Hill’s 19. Bernard also just signed a three-year extension with the Bengals, which could lead to an increased role going forward.
