Surprised nobody has yet pointed out Pete's interview where he talks about originally drafting Britt as a center and then thinking about moving him to center again last off-season. They knew he was going to be raw at RT coming out of a spread offense in college. Need trumps planning sometimes though, and even though he's just now being played at center it was always Plan A.
Height isn't all bad for centers because it correlates with arm length. Pad level is a slight disadvantage but it's not like Russ could see easily over a 6'2" center either so we may as well just go big there; longer arms at center is an advantage for the rest of the line. Lining up a couple of inches back translates into slightly longer times to react when pass blocking and slightly more momentum when run blocking.