This is a pretty close call. I'm going to say linebacker, but it barely edged running back.

Curtis Lofton may not be as good as NFC South foe Jon Beason, but the separation is not that far apart. He really is solid against the run. He knows how to hit runners back in the backfield, and will continue to develop.

Sean Weatherspoon was a really solid pick at number 19. He's a tad undersized, but still gets the job done. Weatherspoon covers an obscene amount of ground, and from what I've seen, he's pretty instinctive. 

Mike Peterson is an linebacker that knows how to lay you flat on your ass. Look at what he did to the Bleacher Report - NFL