Personally, I don't think it should ever solely depend on your starting back, whether it be his skillset or his penchant for injury. Take SJax for example. If he goes down, is his backup really going to be somebody you're willing to plug in every week?!? Some stud backs have solid backups, in which case I would actually reach a bit to cuff. Turner with LT would have been a prime example. Guys run around asking who's the #2 in KC, or here or there, I think its foolish chasing those cuffs. Got a better chance grabbing a ray rice and a chris johnson and a kenny watson, if any ends up getting primary back touches, you can actually start them. It is somewhat of a tightrope you must walk, but unless a backup is half decent, someone you can see plugging into you lineup on a weekly basis, you roll the dice with who you drafted and try and grab the best value available at rb in the later rounds of your draft...