You can't build an entire offensive line in one off-season. They were horrible last season and the Bills basically started from scratch with 4 new starters. Even the one holdover, Dawkins, isn't exactly an all-pro. It's going to take a couple more off-seasons to solidify the OL, assuming that they continue to work on it. Cody Ford is just a rookie and he may develop into a starter, but they're going to bring in other OTs to compete with him (and Dawkins.)