This article is part of our According to the Data series.
Predicting Breakouts from Young Running Backs
"Running backs need to be quick, not necessarily fast. Quickness matters more than straight speed."
- Every NFL television analyst ever
In theory, it seems to make sense that running backs would benefit more from quickness than straight-line speed. They frequently work in traffic and certainly need the ability to make defenders miss in tight areas.
But I've shown in the past that straight-line speed, measured by the 40-yard dash, is highly predictive of NFL success for running backs. The running backs who post the best numbers continually run better than 4.50 in the 40-yard dash.
Yes, there are outliers. But for every Alfred Morris you can name, I can name five Ray Rice's (4.42, believe it or not).
In addition to speed, I want to see which other measurables might be predictive of NFL success for backs. So I charted some NFL Combine numbers for every running back drafted between 2008 and 2012. Then, I compared those numbers to each back's approximate value per year - an awesome judge of production on a per-season basis (so younger running backs aren't penalized for playing only a couple seasons).
Check out the strength of those relationships. Note that there's a negative correlation for every measurable except for the broad jump. That just means the longer a running back's broad jump, the greater his NFL production. Meanwhile, the lower the back's weight, 40 time, vertical, short shuttle, three-come, and draft round, the better