Unofficially, C.J. Spiller was the fastest running back at the NFL Combine, clocking in times of 4.28 and 4.27 in the 40-yard dash. The latter of the two runs was good enough to beat out wide receiver and Clemson teammate Jacoby Ford's 40 time of 4.28, although his time was already official.
That difference was important, because as it turns out, the official times painted a different picture completely. Spiller's fastest time ended up being 4.37 seconds, making him only the second-fastest running back. Who was the fastest? Cal's Jahvid Best, who barely beat out Spiller by running a 4.35. Auburn's Ben Tate had the next best time with a 4.43, and he was followed by Ryan Mathews (4.45) and Joe McKnight (4.47) to round out the top five.
The 40-yard dash time that stood out the most to me was Dexter McCluster's 4.58. I was expecting it to be a lot faster, especially after his first unexpectedly slow time was blamed on a stumble at the start. His second time wasn't any better, though. You can't put too much stock in a couple 40-yard dashes, especially when some people just make plays, but I definitely expected McCluster's time to be faster.