Norton is here and Schotty is gone because the defense improved and the offense regressed. It's that simple.
Why the defense was so bad out of the gate was because we had 6 new starters (Mayowa, Irvin, Brooks, Dunbar, Adams and Blair). Then three of those went down in the first three weeks, so we were in "training camp" during the season.
Adams and Dunlap (re)joined in week 8 (while Griffin went down), but the secondary began to gel and the defense began living up to its potential.
There's no reason to believe that we won't start out playing at a high level even with Griffin gone as we turned it around with him out of the lineup last year. It bodes well if one of the newcomers can beat Flowers out in training camp, but even if they don't I believe the pass rush will be improved and that will make everyone's job easier.