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RBBC, Rushing Concentration, and Outliers

In 1984, James Wilder had 407 carries for Tampa Bay at a time when the league was only beginning to shift away from running back by committee. In fact, by the end of the ’84 season, three of the highest single-season carry totals in NFL history had taken place that year, with Walter Payton and Eric Dickerson joining Wilder as true workhorses. The ’84 Bucs had the most concentrated rushing attack of any team in an era of increasingly concentrated rushing attacks.

Take a look: in ’84, Wilder had 1,544 rushing yards, which represented 86.94% of all Bucs rushing yards. The square of that is 75.58%; sum the squares of all players who gained rushing yards for Tampa Bay last year, and you get a concentration index of 75.87%.

PlayerRushYdsPercSqrd
James Wilder407154486.94%75.58%
Steve DeBerg28593.32%0.11%
Mel Carver11442.48%0.06%
Jack Thompson5351.97%0.04%
Adger Armstrong10341.91%0.04%
Michael Morton16271.52%0.02%
Gerald Carter1160.9%0.01%
Scott Dierking3140.79%0.01%
George Peoples120.11%0.00%
James Owens110.06%0.00%
Total4831776100%75.87%

James Wilder was a one man offense

That was a truly remarkable number in the historical context of 1984. It crushed an NFL record set just one year earlier: the ’83 Rams, with a rookie Dickerson, had a rushing concentration index of 65.95%. Only one other team – the ’81 Oilers — had a concentration index of over 60% when the Bucs hit 76% in 1984.

The average team had a rushing concentration index of 35.5%, and the standard deviation among the teams in 1984 was 13.7%. As a result, Tampa Bay’s rushing concentration index was 2.96 standard deviations above average, known as the Z-Score. That was the 2nd most concentrated score from 1946 to 1984, snugly fit in between the 1966 Patriots (2.93) and 1967 Patriots (2.97).

In 1966, the Patriots led the AFL in rushing attempts and featured a two-back offense with Jim Nance (299 carries) and Larry Garron (101 carries). But since Nance averaged 4.9 yards per carry and Garron just 3.2, Nance wound up rushing for about 74% of the Patriots rushing yards that season. In ’67, New England ran less often, but Nance took a larger share of the load. He had 269 carries to Garron’s 46, and had 76% of all Patriots rushing yards in a very RBBC-centric era. From ’66 to ’67, Nance wasn’t just the top RB in the AFL but in all of pro football. Thanks to his heavy workload, he easily outrushed two HOF RBs in the primes of their career during those seasons.

The table below shows each team that had a Z-Score of at least 1.25 in rushing concentration. Here’s how to read it. In 1991, the Cowboys behind Emmitt Smith had 1,726 rushing yards.1 The squared result of each player’s percentage — i.e., the concentration index — was 82.3%. The standard deviation among all teams that year was 13.9%, and the league average was just 33.9%, giving the ’91 Cowboys a Z-Score of 3.48. In other words, the ’91 Cowboys’ rushing attack was so concentrated for that season that it was 3.48 standard deviations above average. That’s why it ranks 1st in this metric.

RkYearTmTop RBRush YdsSqrdStDevLg AvgZ-Score
11991DALEmmitt Smith172682.3%13.9%33.9%3.48
21994DETBarry Sanders208082.2%13.3%40.2%3.15
32007ARIEdgerrin James144172.4%10.3%40.2%3.12
41999INDEdgerrin James166087.7%15.6%40.1%3.06
51967BOSJim Nance160958.7%10%29.2%2.97
61984TAMJames Wilder177675.9%13.7%35.5%2.96
71966BOSJim Nance196857.8%9.7%29.3%2.93
81961CLEJim Brown219048.5%7.3%27.4%2.89
92002BUFTravis Henry161579.6%12.5%44%2.84
101983RAMEric Dickerson227465.9%11.1%34.5%2.84
111980HOUEarl Campbell265755.8%9.6%28.7%2.83
121974DENOtis Armstrong216547.3%7.3%26.8%2.81
131960CLEJim Brown198247.5%7.5%26.5%2.81
141988DALHerschel Walker199960.1%10.3%31.5%2.78
151968PHITom Woodeshick141148.6%7.7%27.4%2.77
162000INDEdgerrin James186184.7%14.9%44%2.72
172011JAXMaurice Jones-Drew197067.3%11.2%37%2.70
182014DALDeMarco Murray235563.7%10.9%34.9%2.64
191977CHIWalter Payton281147.1%7.5%27.4%2.63
201981HOUEarl Campbell173764%11.7%33.5%2.61
211951NYGEddie Price171337.8%6%22.2%2.60
221975BUFO.J. Simpson297445.2%7.1%27%2.57
231965CLEJim Brown234247.5%7.2%29.2%2.54
241963CLEJim Brown267153.3%9%30.4%2.53
251986RAMEric Dickerson247857.8%10.3%31.9%2.52
261978CHIWalter Payton252646%7.2%28%2.50
271993ATLErric Pegram159757.2%9.1%34.6%2.48
282014PITLe'Veon Bell177361.3%10.9%34.9%2.42
292012MINAdrian Peterson263564.8%11.4%37.2%2.41
301996DETBarry Sanders181074.1%14.2%40.1%2.39
312005INDEdgerrin James170378.8%14.9%43.3%2.39
321985TAMJames Wilder164464.7%11.5%37.3%2.38
331988INDEric Dickerson225755.7%10.3%31.5%2.35
341969BOSJim Nance150645.9%7.4%28.5%2.35
352012TAMDoug Martin183764%11.4%37.2%2.34
362009STLSteven Jackson178663.9%11%38.2%2.34
372015OAKLatavius Murray146354.9%8.9%34.2%2.33
382013DALDeMarco Murray150457.8%9.5%35.8%2.31
391946PITBill Dudley131727.5%4.4%17.2%2.31
401998INDMarshall Faulk148879%15.8%42.8%2.29
411947NYYSpec Sanders293531.8%5.8%18.7%2.28
421989DETBarry Sanders205553%9.2%32.3%2.25
431991DETBarry Sanders193065.1%13.9%33.9%2.24
441997DETBarry Sanders246870%13%41.3%2.21
452004INDEdgerrin James186171.1%13.2%41.9%2.21
461992DETBarry Sanders164468.5%14.2%37.3%2.20
471989INDEric Dickerson186752.3%9.2%32.3%2.18
481979HOUEarl Campbell257147.2%8.3%29.2%2.17
491971CLELeroy Kelly157844.9%8.1%27.5%2.16
501985RAIMarcus Allen226262.2%11.5%37.3%2.16
512006ARIEdgerrin James134175.1%13.8%45.3%2.15
522009TENChris Johnson259261.8%11%38.2%2.15
531963OAKClem Daniels161849.8%9%30.4%2.15
541964CLEJim Brown217150.5%9.5%30.1%2.15
551995DETBarry Sanders176073.3%14.6%42.3%2.13
561999SEARicky Watters142473.1%15.6%40.1%2.12
572001GNBAhman Green170067.7%12.8%40.6%2.12
581998ATLJamal Anderson211976.3%15.8%42.8%2.12
592013CHIMatt Forte182855.7%9.5%35.8%2.09
601950PITJoe Geri165927.4%3.4%20.2%2.09
612010TENChris Johnson173564.2%12.2%39.2%2.06
621949CHHBob Hoernschemeyer108031.8%5.8%20%2.05
631976CHIWalter Payton238741.7%7.1%27.1%2.05
642016CHIJordan Howard173759.1%11.2%36.2%2.04
651973BUFO.J. Simpson310246.2%8.3%29.5%2.02
661993RAMJerome Bettis201452.9%9.1%34.6%2.01
671959CLEJim Brown214950.2%10.2%29.6%2.01
681997OAKNapoleon Kaufman158867.3%13%41.3%2.00
692010HOUArian Foster206963.5%12.2%39.2%2.00
702006STLSteven Jackson180572.7%13.8%45.3%1.98
711977MINChuck Foreman182942.2%7.5%27.4%1.97
721992DALEmmitt Smith213765.3%14.2%37.3%1.97
731986WASGeorge Rogers173251.9%10.3%31.9%1.94
741947PHISteve Van Buren198829.9%5.8%18.7%1.94
751956SFOHugh McElhenny183635.7%5.8%24.5%1.93
761979CHIWalter Payton249245.2%8.3%29.2%1.93
771973WASLarry Brown144945.4%8.3%29.5%1.92
781990DETBarry Sanders192750.1%9.1%32.7%1.92
791954SFOJoe Perry250929.3%3.8%22.2%1.90
802005NYGTiki Barber221271.4%14.9%43.3%1.89
811969WASLarry Brown153242.5%7.4%28.5%1.89
821965NYJMatt Snell149242.8%7.2%29.2%1.88
831958CLEJim Brown252642.2%8.4%26.5%1.88
842004SEAShaun Alexander209566.5%13.2%41.9%1.86
852010STLSteven Jackson159261.8%12.2%39.2%1.86
861971WASLarry Brown175942.4%8.1%27.5%1.84
872008MINAdrian Peterson234559.6%11%39.5%1.84
881964NYJMatt Snell145747.5%9.5%30.1%1.83
891981NORGeorge Rogers229754.9%11.7%33.5%1.83
902006KANLarry Johnson214670.5%13.8%45.3%1.82
912000ATLJamal Anderson121971.2%14.9%44%1.82
921985DALTony Dorsett175058.1%11.5%37.3%1.81
931970WASLarry Brown202139.6%7.1%26.7%1.80
941972WASLarry Brown209042%6.9%29.5%1.80
951992PITBarry Foster215662.8%14.2%37.3%1.79
961968CLELeroy Kelly203141.1%7.7%27.4%1.79
971979PHIWilbert Montgomery242743.9%8.3%29.2%1.78
981948DETCamp Wilson136028.8%5.7%18.7%1.78
992012TENChris Johnson168757.4%11.4%37.2%1.77
1001955BALAlan Ameche183333.9%5.8%23.8%1.76
1011962HOUCharley Tolar174243.2%7.7%29.7%1.75
1021970NYGRon Johnson179939.1%7.1%26.7%1.73
1031949GNBTony Canadeo206129.9%5.8%20%1.73
1041975ATLDave Hampton179439.2%7.1%27%1.72
1052015ATLDevonta Freeman161049.5%8.9%34.2%1.72
1061983ATLWilliam Andrews222953.5%11.1%34.5%1.72
1071954CHIChick Jagade115128.6%3.8%22.2%1.71
1082014CHIMatt Forte146153.5%10.9%34.9%1.70
1091957CLEJim Brown196329.9%3.7%23.7%1.69
1102003NORDeuce McAllister200068.3%14.8%43.5%1.68
1111993BUFThurman Thomas195149.9%9.1%34.6%1.68
1121976BUFO.J. Simpson256639%7.1%27.1%1.67
1132015TAMDoug Martin216249%8.9%34.2%1.67
1142004NYGTiki Barber191664%13.2%41.9%1.67
1151948BDAMickey Colmer181828.1%5.7%18.7%1.66
1161964HOUSid Blanks135345.8%9.5%30.1%1.66
1171952RAMDan Towler184529.4%5.7%19.9%1.66
1182016PITLe'Veon Bell177954.8%11.2%36.2%1.65
1191976MINChuck Foreman201338.9%7.1%27.1%1.65
1201982HOUEarl Campbell79947.6%8%34.4%1.65
1212005CLEReuben Droughns150367.8%14.9%43.3%1.65
1221984ATLGerald Riggs199457.8%13.7%35.5%1.63
1231995DALEmmitt Smith220266%14.6%42.3%1.63
1242004CINRudi Johnson184063.5%13.2%41.9%1.63
1252011ATLMichael Turner184055.3%11.2%37%1.63
1261996NYJAdrian Murrell158763.3%14.2%40.1%1.63
1271979STLOttis Anderson258242.7%8.3%29.2%1.63
1281993DALEmmitt Smith216949.3%9.1%34.6%1.62
1292011TENChris Johnson143855.1%11.2%37%1.62
1301980ATLWilliam Andrews240744.1%9.6%28.7%1.61
1311969BALTom Matte149340.4%7.4%28.5%1.61
1321968SFOKen Willard180039.8%7.7%27.4%1.61
1332001CINCorey Dillon171261.1%12.8%40.6%1.60
1341978HOUEarl Campbell248739.5%7.2%28%1.60
1351952NYGEddie Price163629.1%5.7%19.9%1.60
1361982RAIMarcus Allen108947.2%8%34.4%1.60
1371997NWECurtis Martin148562.1%13%41.3%1.60
1382002NORDeuce McAllister176664%12.5%44%1.59
1392001KANPriest Holmes201861%12.8%40.6%1.59
1401995NWECurtis Martin186665.4%14.6%42.3%1.59
1412008DETKevin Smith133356.9%11%39.5%1.59
1421961GNBJim Taylor235539%7.3%27.4%1.59
1431980STLOttis Anderson218643.9%9.6%28.7%1.59
1441996NWECurtis Martin147162.7%14.2%40.1%1.59
1451953RAMDan Towler215430.4%5.6%21.5%1.58
1461966CHIGale Sayers193944.7%9.7%29.3%1.58
1471981MINTed Brown151352%11.7%33.5%1.58
1481995ARIGarrison Hearst136365.1%14.6%42.3%1.57
1492003BUFTravis Henry167066.7%14.8%43.5%1.57
1502000NYJCurtis Martin147467.4%14.9%44%1.56
1511986NYGJoe Morris224547.9%10.3%31.9%1.56
1521989KANChristian Okoye223546.6%9.2%32.3%1.55
1531990INDEric Dickerson128246.8%9.1%32.7%1.55
1541986NORRueben Mayes207447.8%10.3%31.9%1.55
1552007SFOFrank Gore149356.2%10.3%40.2%1.54
1562009MINAdrian Peterson192855.1%11%38.2%1.54
1571957CHIRick Casares170029.4%3.7%23.7%1.53
1581982PHIWilbert Montgomery83046.6%8%34.4%1.53
1592002SDGLaDainian Tomlinson213763.1%12.5%44%1.52
1601984RAMEric Dickerson286956.2%13.7%35.5%1.52
1611982CINPete Johnson97146.5%8%34.4%1.52
1621998DENTerrell Davis247266.8%15.8%42.8%1.52
1631981ATLWilliam Andrews197351.2%11.7%33.5%1.51
1642015INDFrank Gore143947.6%8.9%34.2%1.51
1652008CHIMatt Forte167356%11%39.5%1.50
1661952SFOJoe Perry191628.5%5.7%19.9%1.50
1671978GNBTerdell Middleton202338.8%7.2%28%1.49
1681972BUFO.J. Simpson213239.9%6.9%29.5%1.49
1692003NYJCurtis Martin163565.6%14.8%43.5%1.49
1701974GNBJohn Brockington157437.7%7.3%26.8%1.49
1711986SEACurt Warner231147.2%10.3%31.9%1.49
1722010CINCedric Benson152457.3%12.2%39.2%1.48
1732015MINAdrian Peterson222247.3%8.9%34.2%1.48
1741962RAMDick Bass168941.1%7.7%29.7%1.48
1752016ARIDavid Johnson173552.7%11.2%36.2%1.47
1762016LARTodd Gurley125352.4%11.2%36.2%1.44
1771960GNBJim Taylor215337.2%7.5%26.5%1.44
1782007SDGLaDainian Tomlinson204655%10.3%40.2%1.43
1791966RAMDick Bass174243.2%9.7%29.3%1.43
1801953SFOJoe Perry224029.4%5.6%21.5%1.41
1812004NWECorey Dillon213560.6%13.2%41.9%1.41
1821992HOULorenzo White164157.3%14.2%37.3%1.41
1831994DALEmmitt Smith195859%13.3%40.2%1.41
1841958PHIBilly Ray Barnes110138.2%8.4%26.5%1.41
1851973GNBJohn Brockington197741.1%8.3%29.5%1.40
1862006CINRudi Johnson164164.7%13.8%45.3%1.40
1871995ATLCraig Heyward139462.6%14.6%42.3%1.40
1881975CLEGreg Pruitt185636.9%7.1%27%1.39
1891980CLEMike Pruitt168141.9%9.6%28.7%1.38
1901996PHIRicky Watters188659.5%14.2%40.1%1.36
1911974BUFO.J. Simpson209436.7%7.3%26.8%1.36
1921983SEACurt Warner211949.5%11.1%34.5%1.35
1932010ATLMichael Turner190055.5%12.2%39.2%1.34
1942011BALRay Rice199651.9%11.2%37%1.33
1951973NYGRon Johnson148840.5%8.3%29.5%1.33
1962004WASClinton Portis177459.5%13.2%41.9%1.33
1972001NORRicky Williams171457.4%12.8%40.6%1.31
1981967CLELeroy Kelly216042.3%10%29.2%1.31
1992016MIAJay Ajayi182550.9%11.2%36.2%1.30
2001971BUFO.J. Simpson133738%8.1%27.5%1.30
2012006NYGTiki Barber215663.3%13.8%45.3%1.30
2021977CLEGreg Pruitt220537.2%7.5%27.4%1.30
2031976WASMike Thomas212736.3%7.1%27.1%1.29
2041962GNBJim Taylor246439.6%7.7%29.7%1.29
2051971GNBJohn Brockington223537.9%8.1%27.5%1.29
2061997GNBDorsey Levens191658%13%41.3%1.29
2071972GNBJohn Brockington213838.4%6.9%29.5%1.28
2081959SFOJ.D. Smith183942.8%10.2%29.6%1.28
2091972NYGRon Johnson202238.3%6.9%29.5%1.28
2102011STLSteven Jackson168151.2%11.2%37%1.27
2111955PITFran Rogel128531.1%5.8%23.8%1.27
2122001WASStephen Davis195556.8%12.8%40.6%1.27
2131990KANBarry Word195444.1%9.1%32.7%1.26
2141990DENBobby Humphrey187244.1%9.1%32.7%1.25
2152003NYGTiki Barber156861.9%14.8%43.5%1.25

It’s impossible to write about rushing concentration and not discuss Edgerrin James. He has six seasons in the top 61, but perhaps more impressively, his teams have 5 of the top 15 most highly concentrated rushing offenses in league history. That’s remarkable. Ditto goes for Jim Brown, whose teams basically finished 1st in 8 of his 9 seasons playing pro football.

  1. This excludes any player who finished the season with negative rushing yards. []
  • sacramento gold miners

    Enjoying this flashback to the underappreciated James Wilder. Here’s a remarkable stat about Wilder we won’t see in today’s NFL, from 1982-87 he was both the leading rusher and receiving on usually terrible Bucs teams. As the picture shows, Wilder had little room to operate, and was keyed on consistently. To give people an idea of how bad the Bucs were during this era, the USFL Bandits actually outdrew them in either 1984 or 1985.

    Also nice to see some recognition for the late Jim Nance. He was a pile-driver, a 235 pound Syracuse product who starred for the old Boston Patriots, and finished up in the defunct World Football League.

    • Thanks, sgm. Yes, Wilder and Nance are underappreciated. How about the Giants Eddie Price? From ’50 to ’52, he was the league’s top rusher on some very good Giants teams. He dominated the rushing concentration for NY during those years.

      • sacramento gold miners

        Did not know about Price until you brought him up. I do remember the publicity Ron Johnson had when he was a multiple 1000 yard rusher for the Giants in the early 70s.

  • LightsOut85

    I like that these past couple articles have completely destroyed the narrative that RBBC is rampant, and a modern phenomenon. I’d imagine someone might argue, “well, maybe the top guy didn’t represent as high of a % of the total back-when, but that’s just because they ran the ball more. Those team-leaders were still workhorses” – but that’s also false. I decided to look at the number of runners with 200+ carries (generously low, when talking about “workhorse”) for 1970-2016, and it followed pretty much the same curve as the concentration plot & the “leader % of total” plot. (#/teams vs year – obviously 70-77 are going to be lower due to having 2 less games a year, but I don’t think changing the threshold to 175 for those years would cause the totals to shoot up).

    We just remember the stars (Brown, Payton, Dickerson, Campbell, etc) and assume they’re the norm, while today sports media gives us a spotlight on both the stars and all the teams using a RBBC.

    • LightsOut85

      I thought I’d come back & add (for anyone reading these at a later date), I went back and added in seasons with just an average of 12.5 att/game (200/16 games), min 10 games (for all years 1970-2016), and pre-90’s was actually similar to post 00’s. I looked at 250 & 275 (/their per game equivalents) and it held true — 275+ it really stood out, 1994-2007 was the peak of “high carry runners” (regardless of % of team yards), while the remaining years bounced around in the same range. (ie: The concentration may be higher now than pre-90s, but the overall rates of high-carries are roughly the same).

      I’d say the conclusion stays the same though, that whatever level of RBBC you want to label the modern rushing-era with, it’s no different than before the 94-07 boom in workhorse backs. I imagine there was a boom partially because more-modern eras tend to have better scouting & finding the super-talented backs who can handle being a workhorse, but it did not continue because the increase in passing led to teams giving more time to backs who can handle complicated passing concepts. (That there are so many passes, it’s not worth it to keep in the potential workhorse if he’s not also a good receiver).

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  • Tim Truemper

    Adding to SGM’s comments about Wilder and Nance. Great to see them recognized in this article. Of course, Wilder is the feature. Nance played a little in the NFC after the merger and had some modest success. And yes, the WFL. WOW. What a career.