Artificial turf sucks.
I can write that without any fear of angry emails. It's not controversial at all. The one common bond that unites sports fans across the world is hatred of fuzzy green parking lots. But maybe it's good for something. In particular, maybe we can use it to get an edge for our fantasy squad. This article will examine how running backs perform on grass vs. turf.
First, some summary numbers. I looked at all running backs who played at least 10 games during the period 1997-1999, and I totalled their performance on grass and turf. I'm interested in the running game here, so I've just listed rushing yards, rushing TDs, and rushing fantasy points (rushing yards/10 + 6*rushing TDs). Here's the data:
rushes yards TD rushing FPT
-------------------------------------------
Grass 17918 71101 488 10038
Turf 16559 65956 438 9224
Our brains aren't really wired to handle that kind of data, so
let's look at it in terms of average per carry.
Yd/Rush TD/Rush FPT/Rush
-----------------------------------------
Grass 3.968 .0272 .560
Turf 3.983 .0265 .557
That's what I call close. In terms of fantasy points per rush,
there is no practical difference at all between how runners
have performed on turf vs. grass. Grass actually comes out
slightly ahead of turf, which is mildly surprising.
That's not the whole story though. For those of you who enjoy brain teasers, try this one on for size: it's possible that every single runner in the entire NFL performs better on turf than on grass, yet the overall grass stats are better than the overall turf stats. How's that? Well, consider an NFL with only two running backs, and suppose they amass the following numbers:
---- Grass --- ---- Turf ---
Rush FPT Rush FPT
---------------------------------------------
Eddie George 100 150 10 20
Jon Witman 10 2 100 30
---------------------------------------------
TOTAL 110 152 110 50
Note: these numbers were completely fabricated for demonstration
purposes.
Both George and Witman were better on turf than on grass, yet
the overall grass stats look much better. It turns out that
way in this simplified NFL because the running backs that
played most often on grass were simply better backs. Could the
same bias be affecting the overall NFL data we saw at
the top of the article?
To get a handle on it, let's look at how many individual backs were better on grass and how many were better on turf. Below, you'll find a list of all backs who had 100 or more carries on both grass and turf over the past three years. Next to each name, you'll see his rushing fantasy points per carry over the same period on both grass and turf.
DIFF = FPT per rush on grass - FPT per rush on turf
(so negative means better on turf, positive means better on grass)
+-----------+
| Fant Pt |
| per rush |
+-----+-----+
LastName FirstName |Grass| Turf| DIFF
------------------------+-----+-----+-----
Hoard Leroy .44 .97 -.53
Hill Greg .39 .65 -.26
Smith Antowain .43 .64 -.22
Levens Dorsey .49 .69 -.19
Smith Robert .48 .67 -.19
Kaufman Napoleon .54 .66 -.13
Staley Duce .42 .52 -.11
Anderson Jamal .51 .60 -.10
Dunn Warrick .42 .51 -.09
Alstott Mike .57 .66 -.08
Means Natrone .52 .59 -.07
Sanders Barry .61 .68 -.07
Davis Stephen .68 .75 -.07
Dillon Corey .57 .62 -.04
Watters Ricky .49 .53 -.04
Bettis Jerome .49 .51 -.02
Wheatley Tyrone .55 .57 -.02
Holmes Priest .61 .63 -.01
Edwards Robert .56 .57 -.01
Davis Terrell .75 .76 -.00
Martin Curtis .49 .49 -.00
Brown Gary .49 .49 .01
Way Charles .60 .57 .02
Lane Fred .56 .54 .03
Murrell Adrian .49 .45 .04
Smith Emmitt .64 .59 .05
George Eddie .53 .47 .06
Allen Terry .53 .47 .06
Faulk Marshall .64 .57 .07
Harris Raymont .57 .48 .09
Abdul-Jabbar Karim .54 .44 .10
James Edgerrin .76 .59 .17
Garner Charlie .70 .52 .18
Taylor Fred .80 .62 .18
Hearst Garrison .65 .45 .20
Warren Chris .76 .53 .23
Bates Mario 1.04 .60 .44
There are 37 backs here. 21 of them were better on turf and 16 were
better on grass, but the overall difference is practically nil.
Specifically, the average DIFF is -.008.
Of course it is possible that the playing surface affects different kinds of runners in different ways. Barry Sanders and Warrick Dunn are frequently cited as guys who are (were, in Barry's case) better on turf -- the general implication being that runners who depend on shiftiness and cutback ability get an extra boost from the better traction turf provides. But the above list does not bear that out at all. There are plenty of power backs at the top of the list, including the biggest turf-hound of them all: Leroy Hoard. Likewise, the bottom of the list (the grass-lovers) contains plenty of small quick backs.
In fact, in terms of styles, there doesn't seem to be any pattern at all to the list. This is an indication that "ability to run better on turf" and "ability to run better on grass" are not really abilities at all. I strongly suspect that simple random chance ordered that list and that it has no predictive value whatsoever. If we re-do this list after the 2000 seasons, it's just as likely to be flipped upside down as stay where it is.
Summing up, I think we have pretty strong evidence here that playing surface should play no role whatsoever in determining which running backs you draft or which ones you start. Turf may give running backs better traction, but it also gives defenders better traction, and apparently it evens out.