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Three years ago, I looked at the single-season leaders in percentage of team rushing yards. Then and now, the top two seasons belonged to Edgerrin James: he had 94% and 92% of the Colts rushing yards in his first two seasons in the league. There were only three other seasons where a running back had at least 90% of his team’s rushing yards: Emmitt Smith in 1991, Barry Sanders in 1994, and … Travis Henry in 2002. In that post, I calculated for each team the percentage of his team rushing yards gained by that team’s top rusher. Then I calculated the league average percentage gained by each team’s top rusher, and plotted how that varied over time. This was intended to measure how running back back committee centric the league was in each year.

For a less rigorous method to measure RBBC-ness, you can see this post, which looked at games with more than 15 carries.

Both methods show RBBC being heavy in the ’70s, and the stud RB era peaking about 10 years ago.  But if you want to measure rushing concentration, a better method is probably to use the formula described yesterday. So for each team, I calculated the percentage of team rushing yards gained by every player on the team, squared that result, and then summed those numbers for each player on the team. You can read yesterday’s post for more info on the methodology, but here were the results for 2016:

RkTmRush YdsSqrd
1CHI173759.06%
2PIT177954.76%
3ARI173552.71%
4LAR125352.43%
5MIA182550.86%
6DAL239848.95%
7SDG151446.23%
8NOR174245.88%
9IND162945.14%
10TEN218942.14%
11NWE187241.97%
12ATL193039.57%
13HOU186239.46%
14CLE171236.99%
15NYJ180636.88%
16BAL149234.42%
17KAN175833.29%
18BUF263432.96%
19MIN120532.03%
20SFO201931.53%
21CIN177730.82%
22NYG142129.81%
23WAS169829.48%
24OAK193329.17%
25CAR181428%
26DEN148427.78%
27PHI181323.44%
28TAM161622.71%
29JAX163322.01%
30DET131021.2%
31SEA159118.56%
32GNB170318.44%

Obviously injuries, rest, and suspension, can significantly impact the data here: Le’Veon Bell missed 4 games last season, or else the Steelers would be number one on this list by a mile. In the 12 games that Bell played in, he was responsible for over 90% of Pittsburgh’s rushing yards.1 Remarkably, the Steelers had a rushing concentration index of 81.95% in the 12 games where Bell was active. And, for what it’s worth, some adjustments for the Bears and Jordan Howard makes sense, too. Howard didn’t play in week 1 and only started the final 13 games of the year. Over those games, he had 80.7% of the Bears rushing yards and Chicago had a rushing concentration index of 66.2%.

But let’s get to the meat of today’s post: what about the variation in average, league-wide rushing concentration over history? Well, take a look:

Tiki Barber is, by far, the all-time leader in yards from scrimmage for the five year period covering a player’s age 27 through age 31 seasons. But he’s also the all-time leader in rushing yards covering those ages, and by a pretty large margin, too. Tiki was great, and he deserves a lot of credit for staying healthy and enduring such a heavy workload. But it does feel a bit like he put those numbers up in an inflated era: Barber’s age 27-31 seasons came from ’02 to ’06, the height of the stud RB era. But it’s not like Barber was a fraud: he and LaDainian Tomlinson were the top two running backs over that five year period.

As to the bigger point? This methodology indicates that running back by committee was gradually phased out over the course of NFL history, rather than some of the bumpier-looking data from prior graphs.  I’m not sure which one is “right” but it’s always interesting to see the results when using different methods.  The other thing that’s clear: the stud RB era peaked in ’06, and then declined over the last decade.  Last year saw a reversal: we’ll have to wait a few years to see if that was the start of a trend, or just an outlier.2

  1. At this point, I should probably note that I zero out all negative rushing yards. Bell had 91.2% of Pittsburgh’s rushing yards during these 12 games, although that drops to 90.3% once you zero out all negative rushing yards. But since you need to square the results and calculate the percentage of team rushing yards, I think it makes sense to eliminate all negative rushing totals. []
  2. Another note: this methodology looks at rushing by all players, including quarterbacks. So that does add another level of complexity to the analysis. []
  • I remember back on the pfr Podcast (*wistful sigh*), Doug Drinen did a segment on James Wilder in which he opined that John McKay was seemingly ahead of the curve in realizing that with the leaguewide reduction in overall running plays one guy could at least come close to handling the load.* That made me realize RBBC wasn’t a new thing, and you’ve written much since about the workhorse RB era having ended about a decade ago.

    I like how the squaring gives you a much smoother line over time. It gives a better sense of a leaguewide adjustment over time than the more purely random-looking earlier graphs.

    *Wilder had 407 carries and 492 touches in 1984 and was even reasonably productive on them, which is impressive. In 1985, he had 365 carries and 418 touches and was much less productive, and his carries continued to decline from there. It might be fair to say that in the end he wasn’t able to handle the load that McKay and “offensive moderator” John Brunner gave him, though HC Leeman Bennett and OC Jimmy Raye continued the experiment for a second season.

    • sacramento gold miners

      James Wilder was a special back, but was trapped on those impotent Bucs teams in the mid 80s. Had some of the power qualities of Mike Alstott, with some of the elusiveness of Warrick Dunn. Had little support, and opposing defenses knew it. Despite the predictability of Tampa Bay’s attack, Wilder still was a force. Put Wilder on a playoff-caliber offense, and his rushing/receiving skills would have been showcased.

      The overuse did wear him down, and he finished up with the Lions and Redskins. I believe his son is on the Bengal’s practice squad.

      • sacramento gold miners

        Oops, James Wilder Jr. is actually a Toronto Argonaut. The CFL preseason starts soon, for those needing a football fix.

    • How prescient of you! I wrote about Wilder today.

      Also interesting: it looks like the Wilder experiment really began in mid-season ’83.

      — In the 7th game of the year, Wilder had 5 carries, while Mel Carver had 12 and James Owens had 4: http://www.pro-football-reference.com/boxscores/198310160tam.htm

      — The next week, it looks like both Carver and Owens were inactive, so Wilder had 20 of the 21 carries that went to a RB: http://www.pro-football-reference.com/boxscores/198310230tam.htm

      — The next week, Owens again had 0 carries, and Carver had just 2 while Wilder had the other FORTY TWO http://www.pro-football-reference.com/boxscores/198310300pit.htm

      This game must have been a turning point. The Bucs were 0-8 and facing the 6-2 Steelers in Pittsburgh. Tampa Bay was a 10.5 point underdog. But the Bucs led 12-0 through 3 quarters, and my guess is Tampa Bay said let’s just keep giving the ball to Wilder no matter what. Pittsburgh won 17-12, though.

      — Perhaps buoyed by what they did last week, along with Wilder’s dominance (and with Owens still out), Carver had just 1 carry while Wilder had 31 carries for 219 yards! This led to Tampa Bay’s first win of the year, 17-12. http://www.pro-football-reference.com/boxscores/198311060min.htm

      — The next week was Wilder’s last of the year, and he recorded 19 of 20 RB carries http://www.pro-football-reference.com/boxscores/198311130cle.htm

      In that game, he suffered cracked ribs that ended his season: http://www.upi.com/Archives/1983/11/14/James-Wilder-who-set-an-NFL-record-two-weeks/2480437634000/

      So really, this 4 game stretch in 1983 — that ended with him getting hurt — marked the beginning of the Wilder era. 20 of 21 carries, 42 carries, 31 carries, and then 19 of 20 carries.

  • I feel like a link to this would be helpful https://en.m.wikipedia.org/wiki/Herfindahl_index

    Let others go into detail on the formula so you don’t have to.

    • Good link, thanks.

  • LightsOut85

    I wonder where (by either measure) this will bottom out in the next 10ish seasons. I can’t imagine it’ll drop much more, given that there’s always an influx of talented college runners (and modern scouting to find those who aren’t playing at big schools), and the desire for backs who can play all 3-downs. I can’t imagine it drops to pre-1980 levels.

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