Originally <a href='https://www.sportsbookreview.com/forum/showthread.php?p=27121081'>posted</a> on 08/02/2017:

Speed Score is Football Outsiders' metric for evaluating running back prospects. It's built on the simple idea that smaller backs tend to run faster than larger backs, so 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:


The average running back who makes it to the NFL will have a Speed Score around 100, with most running back prospects falling between 85 and 110.


Leonard Fournette, however, is not most running backs. Fournette weighed in at 240 pounds, and then went out and ran a 4.51-second 40. That's the fastest time for a back weighing 240-plus pounds since at least 2003, when the NFL's online records begin. It's no surprise, then, that he tops this year's table with a Speed Score of 116.0.