What do you mean, "player he has inherited?" He was a coach in NO and they developed the hell out of their OL, and he should get a lot of the credit. De La Puente, Bushrod, and Nicks all turned out to be good or great players. Even here, he's going to "inherit" players because he's going to have little or no say in what OL they draft or sign. Essentially, Trestman and Emery are going to draft players and it'll be his job to get the most out of them.
I agree in that I could no longer care about what he did in NO, but I'd be more optimistic with his track record than someone who was the OL coach where they had a poor offense and/or a poor OL.