The Auburn back could be more promising than C.J. Spiller, via a key metric
By Bill Barnwell
Football Outsiders has been using the 'speed score' for metric since 1999; here's an explanation relative to the 2008 NFL draft and here are the 2009 results. What follows regards the 2010 NFL scouting combine.
The difference between a 40-yard dash time of 4.37 seconds and 4.43 seconds is 60 milliseconds -- just about half of the time it takes the human eye to blink. To most people, it's imperceptible.
So why should people care about the difference between the respective 40 times of projected first-round pick C.J. Spiller and mid-round prospect Ben Tate?
Because of an historically-effective metric suggesting that Tate might end up the better pro back.
That metric is called Speed Score; it takes two inputs from the Combine. One is that 40-yard dash time, but the other one is more subtle: a player's weight. The logic makes sense: Brandon Jacobs doesn't need to be as fast as Darren Sproles because of the dramatic size difference between the two. Speed Score incorporates the two into a formula that magnifies the miniscule differences in 40-times between players, adjusts the time for the weight of the player in question, and scales the result so that a league-average Speed Score is just about 100 (actually 100.2). That formula is:
Speed Score = (Weight x 200) / (40 time 4)
Speed Scores been computed for every draft since 1999, and it's done a better job of predicting NFL success on a per-carry and cumulative basis than any other statistic on a player heading into the pros, including the "raw" 40-yard dash time. Approximately 20 percent of a player's performance as a pro can be explained by what happens in under five seconds months before he ever steps on a pro field.
The best Speed Score on record is the 123.5 put up by the aforementioned Jacobs in 2005; although he went off the board in the fourth round, his Speed Score suggested that he should be right in line next to Ronnie Brown (121.0), who went 108 picks earlier. More recently, the loaded running back class of 2008 was filled with potential first-round talent; the guy Speed Score identified as the best was a mid-major scatback named Chris Johnson (121.9).
Player Weight 40-Yard Dash Speed Score
Ben Tate 220 4.43 114.2
Ryan Mathews 218 4.45 111.2
Jahvid Best 199 4.35 111.2
Toby Gerhart 231 4.53 109.7
C.J. Spiller 196 4.37 107.5
James Starks 218 4.5 106.3
Montario Hardesty215 4.49 105.8
LeGarrette Blount 241 4.62 105.8
Lonyea Miller 221 4.53 105
Jonathan Dwyer 229 4.59 103.2
Javarris James 212 4.53 100.7
Charles Scott 238 4.67 100.1
Anthony Dixon 233 4.65 99.7
Joe McKnight 198 4.47 99.2
Chris Brown 210 4.58 95.5
Joique Bell 220 4.65 94.1
Stafon Johnson 214 4.66 90.8
Shawnbrey McNeal 194 4.56 89.7
Andre Dixon 205 4.64 88.5
Darius Marshall 190 4.56 87.9
Keith Toston 213 4.7 87.3
Pat Paschall 209 4.69 86.4
Dexter McCluster 165 4.58 75
That's the beauty of Speed Score. It allows us to compare backs both big and small. Of course Chris Johnson is faster than Brandon Jacobs -- he has to be to survive as a pro. Speed Score just quantifies and scales how much faster Johnson has to be.
The metric is far from perfect, though; it doesn't account for a player's health woes, the system he's drafted into, or abilities as a receiver and a blocker -- so it can underrate a player like Ray Rice (99.9), while a player with an elite Speed Score like Darren McFadden (120.0) might very well look worse than his Speed Score suggests. It shouldn't be used as a be-all, end-all way to rank players, but instead as an "athleticism" marker to go along with game tape and a player's constitution.
Now, with all that in mind, we return to Spiller and Tate. Although there was only 60 milliseconds of difference between their respective 40 times, Spiller weighed in at 197 pounds when he was measured in Indy; Tate, on the other hand, was at 220. Accounting for that difference, Speed Score pegs Spiller at 107.5, while Tate is at a Combine-best 114.2.
Considering the difference in their relative grades, that means a lot. The average first-round pick has had a Speed Score of 111.8; and the guys in Spiller's neighborhood aren't particularly impressive: Larry Johnson (106.4), Beanie Wells (105.9), Felix Jones (103.7) and Chris Perry (102.7). Clemson fans will probably compare Spiller to Jones, which is reasonable, but Jones still hasn't hit 1000 career rushing yards as a pro, and plays in a great offense with a very good rushing offensive line in front of him. Spiller would be lucky to end up in a similar situation.
On the other hand, Tate has a mid-round grade on him. Comparing him to backs taken between the third and fifth rounds and with similar speed scores yields a very interesting crop of players: Jamaal Charles (108.7), Kevan Barlow (108.7), Onterrio Smith (109.2), Antonio Pittman (110.5), Chris Brown (111.2), Jerious Norwood (112.1), Michael Turner (116.6), and Musa Smith (118.3). Turner, taken in the fifth round of the 2004 NFL Draft, had the closest figure to Tate; all of the players listed had pro careers, although Pittman was a bust and the talented Smith flunked his way out of the league with drug test failures.
Furthermore, Tate is exactly the sort of player that game film is likely to misrepresent. As part of the annual Auburn change in offensive scheme, Tate lost his job in 2008 when the team moved to a spread offense. As a North-South runner without great raw speed, that makes sense, but when the team moved back to a more conventional style in 2009, Tate ran for nearly 1400 yards in one of the country's toughest conferences. Playing in the spread improved his receiving abilities to the point where they're a plus, too.
The difference between their respective Speed Scores isn't enough to push Tate ahead of Spiller on draft boards, and it shouldn't be; scouts exist for a reason. When you hear the talking heads espousing Spiller's elite athleticism over clips of his 40-yard dash at the Combine, though, don't fall for it. Ben Tate did more for himself at the Combine than Spiller did.
Bill Barnwell is an author of Football Outsiders. You can find his online archives here.
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