The Jerick McKinnon/Matt Asiata Time Share

by Chase Stuart on May 27, 2015

Last year, I looked at the unusual running back by committee in Arizona in 2013. Rashard Mendenhall was the team’s primary back, but he averaged 3.17 YPC that season, while Andre Ellington averaged 5.53 YPC. To measure how “unusual” the split was, I came up with the following methodology: calculate the difference between the YPC of the top two running backs (as measured by carries) on each team, and multiply that difference by the number of carries given to the running back with fewer carries. So for the 2013 Cardinals, the difference between Ellington and Mendenhall in terms of YPC was -2.36; we multiply that by 118 to get a value of -278. For 2014, the most extreme result along this line came in Minnesota.

Matt Asiata had 164 carries for the Vikings but gained just 570 yards, for a 3.48 YPC average. Meanwhile, Jerick McKinnon rushed only 113 times but picked up 538 yards, a 4.76 YPC average. So McKinnon averaged 1.28 more yards per carry than Asiata. Then, we multiply -1.28 by 113, which produces a value of -145, the most extreme of the 32 teams last year.

The reason for this two-step process is that when dealing with backup running backs, you sometimes get small sample sizes. For example, Latavius Murray averaged 5.17 YPC on his 82 carries, but the Raiders split doesn’t count quite as extreme as the Vikings split based on this method. Also, the Cowboys split would look pretty funky if you didn’t penalize RB2s that had only a handful of carries:

Rk	Tm	Running Back	Car	Yards	YPC	Running Back	Car	Yards	YPC	Value
1	MIN	Matt Asiata	164	570	3.48	Jerick McKinnon	113	538	4.76	-145
2	OAK	Darren McFadden	155	534	3.45	Latavius Murray	82	424	5.17	-141
3	IND	Trent Richardson	159	519	3.26	Ahmad Bradshaw	90	425	4.72	-131
4	DAL	DeMarco Murray	392	1845	4.71	Joseph Randle	51	343	6.73	-103
5	PHI	LeSean McCoy	312	1319	4.23	Darren Sproles	57	329	5.77	-88
6	NYG	Andre Williams	217	721	3.32	Rashad Jennings	167	639	3.83	-84
7	TAM	Doug Martin	134	494	3.69	Bobby Rainey	94	406	4.32	-59
8	WAS	Alfred Morris	265	1074	4.05	Roy Helu	40	216	5.4	-54
9	BUF	Fred Jackson	141	525	3.72	Anthony Dixon	105	432	4.11	-41
10	TEN	Bishop Sankey	152	569	3.74	Shonn Greene	94	392	4.17	-40
11	NOR	Mark Ingram	226	964	4.27	Khiry Robinson	76	362	4.76	-38
12	CLE	Terrance West	171	673	3.94	Isaiah Crowell	148	607	4.1	-25
13	NYJ	Chris Ivory	198	821	4.15	Chris Johnson	155	663	4.28	-20
14	CHI	Matt Forte	266	1038	3.9	Ka'Deem Carey	36	158	4.39	-18
15	ATL	Steven Jackson	190	707	3.72	Devonta Freeman	65	248	3.82	-6
16	DET	Joique Bell	223	860	3.86	Reggie Bush	76	297	3.91	-4
17	ARI	Andre Ellington	201	660	3.28	Stepfan Taylor	63	208	3.3	-1
18	SFO	Frank Gore	255	1106	4.34	Carlos Hyde	83	333	4.01	27
19	STL	Tre Mason	179	765	4.27	Zac Stacy	76	293	3.86	32
20	SEA	Marshawn Lynch	280	1306	4.66	Robert Turbin	74	310	4.19	35
21	PIT	Le'Veon Bell	290	1361	4.69	LeGarrette Blount	65	266	4.09	39
22	NWE	Shane Vereen	96	391	4.07	Stevan Ridley	94	340	3.62	43
23	MIA	Lamar Miller	216	1099	5.09	Daniel Thomas	44	168	3.82	56
24	GNB	Eddie Lacy	246	1139	4.63	James Starks	85	333	3.92	61
25	CAR	Jonathan Stewart	175	809	4.62	DeAngelo Williams	62	219	3.53	68
26	DEN	C.J. Anderson	179	849	4.74	Ronnie Hillman	106	434	4.09	69
27	SDG	Branden Oliver	160	582	3.64	Donald Brown	85	223	2.62	86
28	JAX	Denard Robinson	135	582	4.31	Toby Gerhart	101	326	3.23	109
29	BAL	Justin Forsett	235	1266	5.39	Bernard Pierce	93	366	3.94	135
30	CIN	Jeremy Hill	222	1124	5.06	Giovani Bernard	168	680	4.05	171
31	KAN	Jamaal Charles	206	1033	5.01	Knile Davis	134	463	3.46	209
32	HOU	Arian Foster	260	1246	4.79	Alfred Blue	169	528	3.12	282

A few comments:

Darren McFadden averaged 1.17 fewer YPC than Rashad Jennings in 2013, and 1.73 fewer YPC than Murray in 2014. Make of that what you will, but it will be very interesting to see how McFadden fares in Dallas given that history.

We know Alfred Blue was not very effective last year, but this really puts it in perspective. Foster averaged 1.67 YPC more than Blue, the largest differential of any RB1-RB2 combo last season. Blue also had the most carries of any RB2 ^[1]Defined as the running back who was second among running backs in carries. last year, which is why Houston produced such a large value of “unusualness” under this formula.

Not shown: for five teams, their quarterback was actually second on the team in carries. Those five were San Francisco, Seattle, Miami, Carolina, and… Chicago. Ka’Deem Carey had just 36 carries, which is probably a better sign of how much the Bears relied on Matt Forte than Forte’s 265 carries.

You won’t be surprised to learn that Trent Richardson had the lowest YPC of any RB1 last year, narrowly edging out Ellington and Andre Williams. Among RB2s, Donald Brown‘s pathetic 2.62 YPC average truly stands out. That’s the third lowest YPC average by any running back (minimum 75 carries) since 2000.

References[+]

References
↑1	Defined as the running back who was second among running backs in carries.

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