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Foster is thankful for a heavy workload.

Foster is thankful for a heavy workload.

Running back workload is a very difficult topic to tackle, and I don’t expect to make much of an indent into the subject today. But I do want to take a few minutes and look at some ways to measure heavy workloads. One school of thought is that the effect of carries is cumulative: Not only is a 25-carry game more likely to cause a running back trouble than a five-carry game, but it’s more than five times as likely to shorten a player’s shelf life. The cumulative effect of taking hit after hit means that carries 16, 17, and 18 hurt a runner more than carries 1, 2, and 3.

I don’t know if that’s true, but let’s investigate. First, I’m only giving a running back credit for his additional carries after his 15th carry of the game. So an 18-carry game goes down as a “3” and a 25 carry game is a “10.” Using this scoring system, Arian Foster had the highest number of “Carries over 15″ from last season, with 117. Such a list mostly corresponds to the number of overall rushing attempts for a player, but the exceptions could be revealing.

Rk
Running Back
Team
Rsh
15+
1Arian FosterHOU351117
2Adrian PetersonMIN348108
3Alfred MorrisWAS33599
4Doug MartinTAM31994
5Marshawn LynchSEA31587
6Jamaal CharlesKAN28577
7Trent RichardsonCLE26764
8BenJarvus Green-EllisCIN27862
9Stevan RidleyNWE29060
10Shonn GreeneNYJ27655
11Darren McFaddenOAK21654
12Chris JohnsonTEN27654
13Steven JacksonSTL25749
14Ray RiceBAL25748
15Ahmad BradshawNYG22146
16Matt ForteCHI24842
17Frank GoreSFO25841
18Knowshon MorenoDEN13940
19Ryan MathewsSDG18432
20Vick BallardIND21131
21LeSean McCoyPHI20030
22Willis McGaheeDEN16730
23Reggie BushMIA22727
24C.J. SpillerBUF20725
25DeMarco MurrayDAL16124

Foster led the league in both carries and carries above fifteen. But Darren McFadden ranks pretty high on this list thanks to three games with 27+ carries. On the other hand, Stevan Ridley ranked 6th in carries, but he only had one game with more than 22 rushes. McFadden had a 27-carry game in week 6, a 19-carry game in week 7, and a 29-carry game in week 8; in week 9, he injured his ankle and missed a month. Ridley, on the other hand, seemed to be handled pretty well, and one might argue that sharing time with Shane Vereen is good for his long-term health.

We can also use this “Carries over 15″ statistic to get a sense of how teams’ commitment to the running back-by-committee philosophy has waxed and waned over the years. I totaled the number of “Carries over 15″ for the top ten leaders in that statistic every year since the merger. The values themselves1 carry no intuitive meaning, but the relative shape of the curve tells us all we need to know:

car over 15

Contrary to popular belief, RBBC was very high in the early ’70s, and the “stud running back era” peaked in the early part of last decade (this is the sort of thing Doug, Jason, Neil and I used to write about at the PFR Blog).

But over the last few years, RBBC has clearly impacted the league: there has been a significant decline in the number of over high-carry games by top running backs. The number of high-carry games simply isn’t what it was at its peak a decade ago. Foster appears to be an exception, although he can’t touch some of the old numbers (presented at the end of this post). Some have attributed Foster’s declining declining yards-per-carry average to his heavy workload, an idea I addressed here.

But do these high-carry games lead to injury? I looked at the 583 running backs since 1970 to record 200 carries for a team in one season, and then play again for that team in the following season. I thought maybe we’d find some injury evidence indicating that high-carry games lead to missed games the following season. The second-highest season (with a “Carries over 15″ score of 172) belonged to Jamal Anderson in 1998, who played in just two games the next year. And three others in the top ten (Barry Foster ’92, Terrell Davis ’98, and Edgerrin James ’00) also missed significant time the next year.

But that’s misleading. For one, the rest of the top ten remained healthy the next year. In my sample of 583 backs, I broke them down into five groups: the 50 highest backs (in terms of carries over 15), the next 100, the middle set of 283 running backs, the next 100, and the 50 lowest backs. As you can see, it doesn’t seem like the workhorse backs were more likely to get hurt the following year.

Category
Car Ov 15
Rsh
N+1 G
Top 5014036913.5
Next 10010332013.3
Middle 2836426413.6
Next 1003422613.1
Bottom 501921212.5

Anyway, this is just one data point. I hope to look into the issue more over the next few months (or more likely, few years). Finally, I will close with a list of the single-season leaders in “Carries over 15.”

Rk
Running Back
Year
Team
Rsh
Car Over 15
1Eddie George2000TEN403180
2Larry Johnson2006KAN416176
3Jamal Anderson1998ATL410172
4James Wilder1984TAM407169
5Eric Dickerson1986RAM404164
6Gerald Riggs1985ATL397164
7Earl Campbell1980HOU373161
8Ricky Williams2003MIA392156
9Barry Foster1992PIT390156
10Christian Okoye1989KAN370155
11Eric Dickerson1983RAM390154
12Terrell Davis1998DEN392152
13Edgerrin James2000IND387151
14Jerome Bettis1997PIT375150
15John Riggins1983WAS375150
16Terrell Davis1997DEN369149
17Emmitt Smith1994DAL368149
18Eric Dickerson1988IND388148
19Jamal Lewis2003BAL387147
20Earl Campbell1979HOU368146
21Ricky Williams2002MIA383145
22Curtis Martin1998NYJ369144
23Marcus Allen1985RAI380144
24Walter Payton1984CHI381143
25Curtis Martin1999NYJ367142
26Eric Dickerson1984RAM379141
27Curtis Martin1995NWE368140
28George Rogers1981NOR378140
29Edgerrin James2005IND360139
30Charles White1987RAM324138
31Michael Turner2008ATL376137
32LaDainian Tomlinson2002SDG372137
33Emmitt Smith1995DAL377137
34Eddie George1997TEN357135
35Larry Johnson2005KAN336134
36Emmitt Smith1991DAL365134
37John Riggins1984WAS327134
38Curtis Martin2004NYJ371133
39Emmitt Smith1992DAL373133
40Gerald Riggs1984ATL353133
41Walter Payton1977CHI339133
42Clinton Portis2004WAS343132
43Shaun Alexander2005SEA370131
44Edgerrin James1999IND369129
45James Wilder1985TAM365129
46Walter Payton1979CHI369129
47Jerome Bettis2000PIT355126
48Ricky Watters1996PHI353126
49Thurman Thomas1993BUF355125
50Barry Sanders1991DET342125
51Chris Johnson2009TEN358124
52Stephen Davis2001WAS356124
53Earl Campbell1981HOU361124
54Adrian Peterson2008MIN363123
55Clinton Portis2005WAS352123
56Rodney Hampton1994NYG327123
57O.J. Simpson1973BUF332123
58Earl Campbell1983HOU322122
59O.J. Simpson1975BUF329122
60Corey Dillon2004NWE345121
61Rudi Johnson2004CIN361121
62Herschel Walker1988DAL361121
63Gerald Riggs1986ATL343121
64Tiki Barber2005NYG357120
65Edgerrin James2003IND310120
66Emmitt Smith1999DAL329120
67Eric Dickerson19872TM283120
68Rodney Hampton1993NYG292119
69Walter Payton1981CHI339119
70Shaun Alexander2004SEA353118
71Stephen Davis2003CAR318118
72Joe Morris1986NYG341118
73Arian Foster2012HOU351117
74Ahman Green2003GNB355117
75Mark van Eeghen1977OAK324117
76Travis Henry2003BUF331116
77Deuce McAllister2003NOR351115
78Mike Anderson2000DEN297115
79Cedric Benson2009CIN301114
80Steven Jackson2006STL346114
81LaDainian Tomlinson2004SDG339114
82Edgerrin James2004IND334113
83Fred Taylor2003JAX345113
84Clinton Portis2008WAS342112
85Eddie George2002TEN343112
86Shaun Alexander2001SEA309112
87Terrell Davis1996DEN345112
88Willie Parker2007PIT321111
89Edgerrin James2006ARI337111
90Eddie George1998TEN348111
91Terry Allen1996WAS347111
92Dalton Hilliard1989NOR344111
93Willie Parker2006PIT337110
94LaDainian Tomlinson2006SDG348110
95Stephen Davis2000WAS332110
96Adrian Peterson2012MIN348108
97Tony Dorsett1981DAL342108
98Wilbert Montgomery1979PHI338108
99Maurice Jones-Drew2011JAX343107
100Rudi Johnson2006CIN341107

Seeing George atop the list is no surprise in light of one of the craziest stats I’ve ever come across: he had 519 carries during the 2000 calendar year.

Previous “Random Perspective On” Articles:
AFC East: Buffalo Bills, Miami Dolphins, New England Patriots, New York Jets
AFC North: Baltimore Ravens, Cincinnati Bengals, Cleveland Browns, Pittsburgh Steelers
AFC South: Houston Texans, Indianapolis Colts, Jacksonville Jaguars, Tennessee Titans
AFC West: Denver Broncos, Kansas City Chiefs, Oakland Raiders, San Diego Chargers
NFC East: Dallas Cowboys, New York Giants, Philadelphia Eagles, Washington Redskins
NFC North: Chicago Bears, Detroit Lions, Green Bay Packers, Minnesota Vikings
NFC South: Atlanta Falcons, Carolina Panthers, New Orleans Saints, Tampa Bay Buccaneers
NFC West: Arizona Cardinals, San Francisco 49ers, Seattle Seahawks, St. Louis Rams

  1. Note: I pro-rated all non-16 game seasons to 16-games. []
{ 8 comments }
  • Marko Markovic August 12, 2013, 3:47 am

    Shouldn’t you relate those numbers to the overall rushing attempts of any year, to account for “era” in the sense of the overall offesnive environment? Otherwise we probably can’t analyze that curve as being meaningful in terms of RBBC. “Carries over 15″ might just be declining because “Carries” are declining, because people are throwing the ball much more.

    Reply
  • Kibbles August 12, 2013, 9:06 pm

    Your results don’t surprise me, because they match what I’ve seen when I’ve taken a look at it over the years. The backs who get the most carries don’t tend to get hurt more frequently than the backs who don’t.

    I would like to say that there are some selection effects at play here. This isn’t to say that more carries don’t lead to injury, it’s to say that the backs that get more carries don’t tend to get injured more. If you took a random player from the “low carry” group and gave him a Dickerson-like workload, he might snap in half within a month. Coaches, however, are very smart people who have access to lots of data and who get paid big bucks to know their players’ limitations, so when they give an RB a bunch of carries, that serves as a signal that the coach believes he can handle them.

    I think this explains the career of a guy like Mewelde Moore. Moore was a backup for the Vikings and the Steelers, and every time injuries ahead of him pressed him into service, he always wound up outperforming the guys ahead of him on the depth chart… but he never got a starting job. In fact, I believe four different coaching staffs all had Mewelde Moore, and they all used him exactly the same way- change of pace back and emergency backup. The fact that those different coaching staffs all refused to give him a larger workload is indirect evidence that those coaching staffs, who all saw him in practice every day and had a good idea of what he was capable of, all agreed that he couldn’t handle it.

    In other words, a large workload might wear a runner down, but you shouldn’t downgrade backs that receive a large workload under the assumption that they’re going to get worn down.

    Reply
  • shawn August 19, 2013, 5:19 pm

    I’m currious how the number of 15+ carries as a percentage of total carries impacts n+1. Maybe the problem isn’t the 370 ‘threshold’, rather a percentage threshold. For example Larry Johnson’s 15+ carries amounted to 42.3% of his total usage in 2006. Similar percentage for Jamaal Lewis in 2003.

    Reply

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