It's only fitting that, in a draft where most experts have only one running back being selected in the first round, Football Outsiders' Speed Score champion from the 2013 NFL combine is a third-day prospect at best -- or at least he was until Sunday. After running the 40-yard dash in an official time of 4.37 seconds and weighing in at 227 pounds, Arkansas running back Knile Davis blew away the competition with a Speed Score of 124.5.
Introduced on ESPN Insider back in 2008, Speed Score is Football Outsiders' metric for evaluating running back prospects. It's built on the simple idea that, because smaller backs tend to run faster than larger backs, we should be more impressed by a 4.5-second 40-yard dash from a 220-pound back than the same clock reading from a 170-pound back. As such, Speed Score incorporates a back's official time in the 40-yard dash with his weight to produce a measure of his speed given his size using the formula, (Weight * 200)/(40 time^4). As a guide, we consider a 100 Speed Score as average, with anything below 80 serving as a giant red flag, and anything above 120 serving as a giant neon sign.
To put this in context of our previously discussed prospect: Knile Davis' 124.5 Speed Score this year is off-the-charts good.