Im as optimistic as they come, but how exactly do you expect the Jets D to be a strength when they've literally lost basically every one of their starters??
The Jets lost starters who are no longer capable of being good starters on any defense, due to age and injury. Pace, Scott, Thomas, Bell, Pouha are all on the wrong side of 30 and have lost their ability to produce on a consistent, high level. It's time to let them go and replace them with younger, faster players. Devito would have been nice to have but Ellis will take his spot. The one loss that might really hurt is Landry, but the Jets have two young safeties from last year plus the upcoming draft and FA to find his replacement. The D still has Wilkerson, Coples, Harris, Cro and Revis (at least for now). Put some young decent players around them, together with Rex's schemes and the D will be fine.