I am very interested in seeing how they play this year. Zimmer's D and what he demands from his players on being in the right spot all the time and not freelancing is crucial, and I think it takes DB's at least one - maybe two - full seasons to grasp/buy in to what he is teaching, why he wants them do it his way. Deon Sanders was/is a HUGE believer in the Zimmer D philosophy for DB's. Says a lot coming from the best ever at his position (IMO).
Tread needs to believe in himself and run crisp precise routes. Stop thinking and just do it. Let your natural abilities shine through. I think he had a hard time digesting the play book / understanding the route tree and his correct spots to be on the field / Dealing with his old injury. All these things derailed him last year. His head was spinning.
Trust in Zimmer's coaching and they can be very good players. They have the physical tools.