Plus when Byrd came back it didn't appear he had the wheels to do single high. Possibly he never did, as I've understood that he was in a two high in Buffalo. But Williams can do it.
Byrd was never a single high guy in Buffalo. He played a lot of Robber coverage but never really played a true centerfield. He never had the range but putting him in robber coverage allowed him to jump a lot of routes. That and the secondary he left in Buffalo was better than the secondary he came to in 2014.
When he did play single high he would play nearly an extra 7-8 yards back to allow him to make up ground via angles and the distance the ball had to travel. Yet again that style was easier to play with a better secondary in buffalo. Worse secondary + injury = no Byrd plays until last year when the secondary/defense saw a stretch of improvement.