I would say neither. Running backs have such a short career, generally, that I don't blame anyone to try and get the maximum they can RIGHT NOW. However, that's the reason you don't pay running backs a ton of money. There are some running backs that last (like Travis Henry) but they are rare and the back that, to my eyes, seemed the most likely to be sustainably great was Ezekial Elliot and you saw how that contract extension worked out. I think Cook will go elsewhere to maximize his payday and the Bills will let him....and that's okay.