They have a chance to have an elite DL. Hardy, Craw, Law, Mince could become their best group up front in many years. Not a lot of proven depth behind them, but Gregory is certainly intriguing.
Linebackers are questionable just in terms of availability. Hitch played well last season. Wilson is a promising addition. Lee and McClain could potentially form a very dynamic pairing, but Lee will have to prove he can stay healthy and McClain is basically the definition of a question mark right now.
Secondary has more depth than last year but is mostly filled with inconsistent players. How they perform if the team is able to muster a pass rush is the biggest defensive question for me.
Last season the team was actually awful in yards per play. They overcame that with help from TOP. But more importantly to me was their ability make big plays. They forced a lot of stops and turnovers in a timely fashion. From early on it was surprising to watch the seemingly marginal guys they rolled out there actually make the plays their positional antecedents had not. With an infusion of talent, you'd hope that the big plays would increase or at the least maintain.
The problem is that the schedule is going to be working against them early. They face four potent offenses with two of their best players out. Establishing a similar pattern to last year in terms of the offense and defense helping each other will be vital in those early games.