I'm not inclined to take a Center at 52. It would help us of course, but given that we should be able to find Center and RB in rounds 3/4 it makes more sense to me to get after the more difficult to find positions if they're available at 52.
So for me that would be developmental LT (guys with the size and feet are gone by early round 2 in most drafts it seems) or impact types like an OLB, CB, etc., who can give our defense a shot in the arm. Nickelbacker would be one of those too btw, it's not a glorious position to be a primary sub option but in this particular defense the way to replace Littleton is to draft a SS who can cover a bit and might be able to transition to LB (guy like Chinn for example).
All that aside if Snead moves down from 52 then I think Center becomes more likely as our first pick. But I really hope they get a "dropped on their board" type at 52 instead, an impact type talent who takes the edge off not having that first round pick.