In my view and from my experience of running the ZBS, it starts with the Centre and works out from there. We're doing pretty well with Pouncey. If you have a Centre that can reach 2techs which he can, then you start in a great position.
As for the guards, I think it's clear from the staff that with the pick ups in the Draft and FA that they want to upgrade the guard spots, including Incognito - so it's going to be an interesting camp battle here.
Tackles - It looks like it settled with Martin and Clabo but I'm really keen to see where Yeatman is and wouldn't be surprised to see him get some reps at Guard to up his experience and ease him in with having support around him.