After 4 games, it's clear that the Bengals toughest opponent has been... the Bengals. I have yet to see a team that they don't have the potential to beat when they don't beat themselves.
In the first 3 games, the offense appeared unstoppable except when it had unforced errors; namely penalties and ball security issues. Those seemed to be largely corrected in game 4. Unfortunately there was general malaise in week 4 and the QB seemed to have a particularly bad game. No reason to believe that will be a recurring problem.
Despite the average yards, BJGE has generally been solid. He's in many plays where 1 yard equals success. On early downs, he seems to get a consistent 3-5 runs a high percentage of the time. He's at most a threat for 8-10 yards but he's good at grinding tough yards and putting them in manageable situations.
All the other skill players are legitimate threats to break a big one at any time. When the offense can consistently hit 80% of their potential they'll be fearsome.
As is the norm the last few years, the defense has be solid and will continue to tighten the screws as the season progresses. Run D has generally been stout. Pass rush seems to be a half a step late because everyone is doing quick throws against them. Secondary has been doing relatively well considering how thin they are.
Maualuga, who was widely expected to be a weakness, has been doing very well this year. I think removing the burden of forcing him to be a leader and calling the plays has allowed him to focus on playing to the best of his abilities. The other preseason concern was safety but Iloka has been very solid there.
Overall, few glaring weaknesses and they should only improve as guys get healthy.
Place kicking has been solid, punting has been great, and return games have been okay. Nothing to be panicked about here.
Like everything else, improvements can be made but play calling generally seems to be good and time management has not been horrible. I'll never say Marvin is the greatest game day manager, but I'm scratching my head a lot less this year.