Top RB prospects for 2015

Todd Gurley is poised for a big 2014 season. Dale Zanine/USA TODAY Sports

Soon after the 2014 NFL draft concluded I released my "too-early" Big Board for the 2015 NFL draft, a ranking that includes players who will be underclassmen during the 2014 college football season. It goes without saying that these rankings are preliminary, as I have hundreds of hours of evaluation ahead on the 2015 class.

A couple of important notes about the rankings below:

• This isn't a straight "top 10" list, because I've split these between seniors and underclassmen. I think it's important to rank seniors alone, as those are the only players I can guarantee will be a part of the 2015 NFL draft process.

• In some instances I've included more than 10 players; if two or three guys are extremely close on my board, I simply tacked on the names.

With those parameters in mind, here's an early look at the top running back prospects for 2015.

Top five senior running backs

1. Ameer Abdullah, Nebraska Cornhuskers: Nebraska hasn't churned out running backs the way it did in the Tom Osborne era, but Abdullah is as productive a back as they've seen in Lincoln since Ahman Green. He leads all FBS players in career yards from scrimmage, and offers value not merely as an explosive runner, but as a pass-catcher, with 50 catches over the past two seasons.

2. Karlos Williams, Florida State Seminoles: Teammate Devonta Freeman was drafted by the Atlanta Falcons, but nobody on the Florida State roster was as impressive on a per-carry basis as Williams last year -- he piled up 8.0 yards per carry and at over 220 pounds, is a great blend of speed and power. The former defensive back could push to be the top back in the 2015 draft.