Kirby Lee
Feb 6, 2016; San Francisco, CA, USA; Minnesota Vikings running back Adrian Peterson poses with the FedEx Ground Player of the Year trophy at the NFL Honors press room at Bill Graham Civic Auditorium. Mandatory Credit: Kirby Lee-USA TODAY Sports
Running back is arguably the most difficult position to rank in the NFL today. From year to year, very few of the league's top runners continue performing at a high level.
Whether it's because of injury, change of team or scheme, the list seems to vary more than any other position group.