Running back class has much to prove

Clemson's C.J. Spiller is the clear-cut No. 1 running back in this year's class, and while he is not expected to take part in all drills at the combine, we are interested to see how his 40-yard dash times look. Specifically, we'll be looking at Spiller's 10- and 20-yard splits to help confirm that he is the most explosive offensive skill player in this year's draft.

After Spiller, there's a handful of backs, each with something specific to prove.