I don't believe their defense is as bad as it may seem. I thought they played fairly well last season considering the circumstances. Once again last year they were hung out to dry on the field for the majority of each game by an inefficient offense, & they had too many injuries at key positions. When a team runs a 3-4 thats predicated on bringing extra pressure with the ILBs & OLBs you have to have good or better CB's that can nail it down in press-man coverage without help from the safeties. You also need a mainstay at NT to help open things up for the blitzing LB's. The Bears Basically trotted out a starting defense full of rag tags & backups outside of a few exceptions, & they are the key reason the Bears were competitively close in most of their games during 2016 in spite of their terrible overall record.
Now the Bears have addressed the vital needs at CB with decent talent & have Goldman healthy on the nose. If healthy I do think that this can & will be a defense ranked inside the top 10, again if healthy. Personally I don't believe the Bears are nearly as bad as some may want to imply, even last years team should been significantly better minus the numerous injuries at key positions. If Pace manages to now address the OT & WR positions with halfway legitimate talent moving forward, IMO there is no reason that the Bears shouldn't be a factor that one has to figure in with future contender discussions. Especially if Trubisky becomes the type of QB that I believe he will become in a year or two.
