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Some Initial Thoughts Running Backs

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“Based on the following formula:”

Peterson and Foster each finished in the top four in rushing first downs

Peterson and Foster each finished in the top four in rushing first downs.

I’ve spent a lot of time this offseason looking at how to grade wide receivers; today I wanted to get some initial thoughts down on paper on running backs.

I’m short on time today, which means a lot of data and not so much theory. One of the more underrated statistics to measure running backs is the number of first downs they produce. I don’t like using Yards per Carry for running backs because that metric is pretty sensitive to outliers. But by using rushing first downs, perhaps we can smooth things out.

We know that the value of a touchdown is about 20 yards, but what is the value of a rushing first down? Being short on time, I took the easy way out. Pro-Football-Reference has produced Expected Points Added for each team’s running game going back to 2000. I decided to run a regression on the team level to best predict rushing EPA based on four rushing statistics. The R^2 was 0.77, but more importantly, here was the best fit formula:

EPA = -16.6 -0.58*Rush + 0.067*Rush_Yd + 1.43*Rush_TD + 1.08*Rush_FD

What interests me is the relationships between the variables. Rushing touchdowns are considered 21.3 times as valuable as rushing yards, which happens to fit in well with our previous assumptions. But more importantly, this tells us that a rushing first down is worth 16.1 rushing yards. That seems pretty high to me, and I reserve the right to adjust this later, but for now, let’s adjust down and say the value of a rushing first down is 15 yards. Now what?

There were about 12,000 rushes by running backs last season. If we give each running back 20 yards for each rushing touchdown and 15 yards for each rushing first down, then the average running back gained 8.05 Adjusted Yards per Carry last year. From there, we can — by making some broad and some inappropriate assumptions — come up with a value over average statistic.

Let’s start with Adrian Peterson. He rushed 348 times for 2,097 yards last year, and also picked up 88 rushing first downs and 12 rushing touchdowns. That gives him an average of 10.5 AY/C last year, nearly 2.5 AY/C above league average. That means over the course of his 348 carries, he is credited with 856 Adjusted Yards ((Based on the following formula: ((10.5-8.0)*348).)) above average. If we do that for every running back, we get the following table:

RkRunning BackTmRshRshYdYPCRshTDRshFDAY/CVALUE
1Adrian PetersonMIN34820976.03128810.51856
2C.J. SpillerBUF20712446.0165310.43493
3Alfred MorrisWAS33516134.8113869.44467
4Stevan RidleyNWE29012634.3612839.48414
5Marshawn LynchSEA31515905.0511729.17355
6Andre BrownNYG733855.2782612.81348
7Frank GoreSFO25812144.718689.28318
8Jamaal CharlesKAN28515095.295638.96260
9Mike TolbertCAR541833.3972412.65248
10Ahmad BradshawNYG22110154.596589.07226
11Bryce BrownPHI1155644.94339.9214
12Cedric PeermanCIN362587.1711011.89138
13Brandon BoldenNWE562744.8921810.43133
14Willis McGaheeDEN1677314.384448.81127
15David WilsonNYG713585.044179.76122
16Michael RobinsonSEA12494.0801016.58102
17Kendall HunterSFO723715.152189.46102
18Justin ForsettHOU633745.941149.5997
19Delone CarterIND321223.8131110.8489
20Dion LewisPHI13695.311613.7774
21Danny WoodheadNWE763013.964208.9669
22Arian FosterHOU35114244.0615788.2569
23Doug MartinTAM31914544.5611648.2667
24Ben TateHOU652794.292189.0666
25Evan RoysterWAS23883.832810.7863
26Jacob HesterDEN17814.762511.5359
27LaMichael JamesSFO271254.6301010.1958
28Maurice Jones-DrewJAX864144.811218.7157
29Joique BellDET824145.053168.7154
30Darrel YoungWAS14604.290711.7952
31DuJuan HarrisGNB341574.62289.3243
32Bernard PierceBAL1085324.931248.4443
33Joe McKnightNYJ301795.97079.4743
34Montell OwensJAX422094.981109.0241
35Chris IvoryNOR402175.43279.0540
36Lamar MillerMIA512504.91128.8240
37Shaun DraughnKAN592333.952168.6938
38DJ WareTAM11514.640511.4537
39Shane VereenNWE622514.053158.6537
40Marcel ReeceOAK592714.590168.6636
41Lex Hilliard2TM9333.67051236
42Ray RiceBAL25711434.459528.1835
43Ryan Grant2TM321324.13289.1334
44Cyrus GrayKAN7446.290312.7133
45DeMarco MurrayDAL1616634.124398.2532
46Ronnie BrownSDG462204.780128.730
47Mike GoodsonOAK352216.31068.8929
48Darren SprolesNOR482445.081108.6328
49Vonta LeachBAL9323.561310.7825
50Jorvorskie LaneMIA13131259.8523
51Brandon JacksonCLE8546.750210.520
52Armando AllenCHI271244.59168.6717
53Daryl RichardsonSTL984754.850228.2116
54Michael BushCHI1144113.615288.1714
55Greg JonesJAX581.60310.613
56Anthony AllenBAL16613.81148.8112
57Robert HughesIND155012012
58Travaris CadetNOR155012012
59Collin MooneyTEN5193.8029.89
60Stanley HaviliPHI6223.67119.59
61Stefan LoganDET3175.670110.678
62Bruce MillerSFO5183.6029.68
63Chris RaineyPIT261023.92258.358
64Lance BallDEN421583.761118.175
65Isaiah PeadSTL10545.4028.44
66Quinn JohnsonTEN451.25028.753
67Lawrence VickersDAL3113.67018.672
68Bernard ScottCIN8354.38028.131
69Owen SchmittOAK210.50180
70Kregg LumpkinNYG9424.670280
71Jamie HarperTEN19301.58347.89-3
72Anthony DixonSFO21783.71237.76-6
73Bilal PowellNYJ1104373.974247.97-8
74Taiwan JonesOAK6213.5016-12
75Isaac RedmanPIT1104103.732287.91-15
76Johnny White2TM8344.25016.13-15
77Brandon JacobsSFO571.4014.4-18
78Lance DunbarDAL21753.57057.14-19
79Chris OgbonnayaCLE8303.75015.63-19
80Da'Rel ScottNYG691.5014-24
81Tashard ChoiceBUF471934.11197.4-30
82Keith TostonJAX17744.35026.12-33
83Knowshon MorenoDEN1395253.784327.81-34
84LeGarrette BlountTAM411513.68277.22-34
85Jason SnellingATL18633.5036-37
86Leon WashingtonSEA23833.61136.43-37
87Fred JacksonBUF1154373.83267.71-38
88Le'Ron McClainSDG14423025.14-41
89John KuhnGNB23632.74146.22-42
90Jalen ParmeleJAX401433.58096.95-44
91Ronnie HillmanDEN843273.891197.52-44
92Mikel LeshoureDET2157983.719477.83-47
93Richard MurphyJAX23924035.96-48
94Toby GerhartMIN501693.381117.08-48
95Robert TurbinSEA803544.430167.43-50
96Montario HardestyCLE652714.171127.25-52
97LeSean McCoyPHI2008404.22457.78-55
98Brian LeonardCIN331063.21076.39-55
99Jeremy StewartOAK251014.04035.84-55
100DeAngelo WilliamsCAR1737374.265337.7-60
101Vick BallardIND2118143.862527.74-64
102Kevin SmithDET371343.62156.19-69
103Mewelde MooreIND13201.54012.69-70
104Peyton HillisKAN853093.641197.22-70
105Felix JonesDAL1114023.623247.41-71
106Baron BatchPIT25491.96145.16-72
107Reggie BushMIA2279864.346437.71-76
108Curtis BrinkleySDG391152.95086.03-79
109Phillip TannerDAL25612.44044.84-80
110Donald BrownIND1084173.861237.24-87
111Rashard MendenhallPIT511823.57096.22-93
112Pierre ThomasNOR1054734.51177.12-97
113Kahlil Bell2TM29762.62044.69-97
114James StarksGNB712553.591136.62-101
115Daniel ThomasMIA913253.574156.92-102
116Jackie BattleSDG953113.273196.91-109
117William PowellARI592163.660106.2-109
118Mark IngramNOR1566023.865297.29-118
119Matt ForteCHI24810944.415457.54-127
120Jacquizz RodgersATL943623.851166.62-134
121Cedric BensonGNB712483.491105.89-153
122Jonathan DwyerPIT1566233.992297.04-157
123Chris JohnsonTEN27612434.56467.44-168
124Jonathan StewartCAR933363.611146.09-182
125Ryan WilliamsARI581642.83084.9-183
126Michael TurnerATL2228003.610407.21-187
127BenJarvus Green-EllisCIN27810943.946557.33-198
128Chris WellsARI882342.665115.67-209
129Steven JacksonSTL25710424.054497.23-211
130Shonn GreeneNYJ27610633.858527.26-218
131Ryan MathewsSDG1847073.841356.8-229
132LaRod Stephens-HowlingARI1113573.224155.96-231
133Rashad JenningsJAX1012832.82165.57-250
134Alex GreenGNB1354643.440175.33-367
135Trent RichardsonCLE2679503.5611386.52-409
136Darren McFaddenOAK2167073.272355.89-466

I think I like this better than a system based purely around yards per carry, but there are some obvious drawbacks. I don’t like that Andre Brown is ahead of Arian Foster, and in general, Foster seems way too low (you can read more about my thoughts on him here). And obviously it’s hard to separate out a player’s ability from his production, and I still like Trent Richardson even if he didn’t produce in an unfavorable situation last year.

Four years ago, I ran a series on the most dominant running backs of all time. At some point, I plan to revisit that topic. I dismissed the idea of using yards per carry to grade running backs then based on the following logic:

Is 270/1100 better than 330/1100? One argument that I’ve certainly used before is “they got the same number of yards, but the first guy’s team had an extra 60 plays with which to gain more yards!” The natural response to that is “why would a coach give a RB 330 carries if he was only getting 3.6 per carry?” From there, we have a two different answers. Either: a) the RB wasn’t that good but either the coach was dumb or the backups were really bad, or b) the RB was good and his YPC is misleading.

Once again, with rushing, I think median carry is a more telling number than average carry. Yards per carry is not a very good measure of central tendency. On the other hand, we can infer that if a RB is getting a high number of carries, he’s doing something right. Carries themselves are highly correlated with greatness.

Terrell Davis, Edgerrin James, Curtis Martin, LaDainian Tomlinson, Eric Dickerson, Clinton Portis, Eddie George, Walter Payton, Barry Sanders, Jim Brown, Emmitt Smith, Ricky Williams and Earl Campbell. Those are the RBs with over 19 carries per game for their careers. A RB that gets carry after carry is doing something right. Maybe he’s consistently getting gains, maybe he’s running hard despite a bad OL, or maybe he’s able to kill the clock without fumbling. All of those things are good. A list of the top RBs by yards per carry? Jim Brown, Barry Sanders, Paul Lowe, Robert Smith, Joe Perry, Wendell Tyler, Greg Pruitt, James Brooks, Tiki Barber, Hugh McElhenny, O.J. Simpson, Fred Taylor and Charlie Garner all have career averages over 4.6 YPC. Ignoring the overlap, I’d prefer the first list.

Remember, teams can choose to pass instead of run. So if a RB is getting 350 carries, it can’t be just because his RB teammates are bad. It’s got to be because the team’s QB is bad, too. And if a team’s QB is bad, its other RBs are bad and one guy keeps getting carry after carry, then he’s pretty valuable to his team. And if year after year he gets these carries, he’s definitely doing something right. A RB with 1600 yards on 400 carries may be just as valuable or dominant as one with 1600 yards on 325 carries. After all, the obvious question for the latter RB is — why didn’t he get more carries? Perhaps the former RB was getting three and four yards on every carry, a very valuable trait.

I’ll open up the rest of the post to you. What formula would you devise to grade running backs? Leave your thoughts in the comments.

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