Speed is power in the NFL, and people are now taking note of Onterio McCalebb, a running back out of Auburn that ran a 40 yard dash in just 4.21 seconds. That time, is unofficial, and even if the official time is over Chris Johnson's 4.24 time, it's still extremely impressive to see.
McCalebb hasn't been mentioned as a big name prospect this offseason. In four years at Auburn, his best season was in 2010, when he ran for 810 yards and nine touchdowns. They're not bad numbers, but certainly not anything to write home about.
One of the primary reasons fast running backs are on the rise in the NFL is due to the development of the passing game. With such an emphasis on passing the ball, teams want to make sure they have a running back that can catch balls out of the backfield and turn dump off passes into big plays. That's what speed allows you to do.
We'll see what the reception for McCalebb looks like after the combine is over, but his draft stock definitely ticked forward today. Even as an unofficial time, 4.21 is stupid fast, and that's the kind of speed every NFL team wants.