There is a difference between hoping/ thinking something is possible vs expecting something to happen. I don't think it's fair to Hendricks to expect him to be improved.
From his rookie season? I think he will be improved. You can never really know the extent of injuries, but gap years for young players seem to lead to development regularly. I expect him to be better, but Cody would be my pick for the most improved given how low his starting point is. If you thought he was due for big improvement after his rookie year I don't think it's an unreasonable pick.