I think that the original post is correct in a lot of ways, even if some comments could be considered as harsh or overreacting by some "true" fans. It's just a very objective and unemotional view.
1) Each part, offense or defense, starts and falls with the Lines. Give Carr more time, and you get better production. Give Davis or whoever some lanes ... The possiblities of Carr and Davis and AJ with all that other Receiver you've got are amazing. It's just that the word possiblities has still to be used. The play calling looks conserative sometimes, BTW.
2) ImHO the defense still lacks a true leader/playmaker. One guy, who is leading by action as vocal as well. Like a DT or LB (in the 3-4 system) who can make HIS Defense better and raise the level of play forcing an off coordinator to account for him. It's a lack of personnel that some expansion teams already have had, cause that players are hard to get.