Projecting top running back prospects in 2017 NFL draft

Measuring two of the NFL Draft's top RBs (2:58)

ESPN Sport Science examines what sets Dalvin Cook and Alvin Kamara apart from the rest of the running back class and who they compare to in the NFL. (2:58)

Last year, Football Outsiders developed BackCAST, a metric that projects the likelihood of success for running back prospects in the NFL draft. Historically, a college running back with a good size-to-speed combination and high average yards per carry and who represented a large percentage of his college team's running attack is more likely to succeed at the pro level. BackCAST considers these factors and projects the degree to which the running back will exceed the NFL production of an "average" drafted running back during his first five years in the NFL.

For example, a running back with a +50 percent BackCAST is projected to gain 50 percent more yards than the average drafted running back. BackCAST also projects whether each running back is likely to be heavily involved in the receiving game or is more of a ground-and-pound back.

This year, BackCAST suggests we have an amazing 2017 class of running backs. Indeed, not one, not two, but three running back prospects would make the list of the top 10 prospects ever in BackCAST's database (since 1998). This class also boasts a high number of strong midround prospects, making this the ideal draft for a team with a need at the halfback position.

For an explanation of how BackCAST works, check out the full detail at the bottom of the article.

What follows is a ranking of the top running back prospects for 2017 according to our model, as well as one fairly highly regarded prospect whom the model suggests as a likely bust:

1. Leonard Fournette, LSU

BackCAST score: +142.2 percent
Type of back: Balanced
Similar historical prospects: Ricky Williams, Willis McGahee

Fournette has an amazing size-and-speed combination. The average drafted running back is 216 pounds and runs a 4.55 40-yard dash. Fournette, by contrast, is faster than the average running back at 4.51 seconds and much heavier at 240 pounds. (He dropped to 228 pounds at his pro day, but unfortunately for football analytics enthusiasts, he did not run the 40 again.)

Fournette was also no slouch when it came to collegiate production. In his career, he had significantly more rushing attempts than the typical prospect, even though he missed a good third of his junior season because of injury (and also, perhaps, because of a desire to preserve his health for the draft). Fournette also averaged more than 6.2 yards per attempt in his career.

Teams are right to hesitate before using a first-round pick on a running back, but Fournette's numbers are so good that it's hard to argue that teams at the top of the draft who have a need at running back should pass on him.