I dont want to make to generic of a response, but I think its a combination of those things.....and its nothing more than while on "any given sunday" you can beat a team, in the long run the good teams better the less than good teams more times than not.
I personally have not seen bad playcalling, as much as lack of execution. The 2nd and 3rd down and 1 yard plays are more aberration where you try to throw on 2nd down and then you may out think yourself on 3rd...but its only 1 play (the 3rd down one) that you really question since it didnt work and you would tend to say, you can get 1yard on the ground. Any way, I see the same plays being called during all 5 games so far, but its the successful execution of the plays that has changed.
Basically if you break the season into quarters we were 2-2 in the first 4 games, now we are 0-2 to start the next quarter of the season. We have lost 3 in row more from our lack of execution on offense and the defense has only had two bad series when you wanted them to really shut a team down for momentum purposes. The opening series to start the game, and to start the 3rd quarter following Ronnies run. Both Gus and the Defense (more from injuries and exhaustion outside of those two series above) played poorly. Also the special teams is not without fault. Twice this year they have given up big returns following a Dolphins score when field position changes how our D would attack. Its a total 3 way team failure all year. They are all just taking turn unfortunately.
The KC game was just a bad all around game for the enitre team, its happens. It should be used as a measuring stick for the entire season. It was only 1 game.
I agree that Gus' accuracy has slipped in the last game. While he has missed on the deep ball consistenly throughout the year (some of which is the receivers fault as well), the chiefs was the first game where you could see he missed on shorter routes. But I give him and the coaches the benefit of the doubt that this is the exception and not the rule as to whether he gives the team the best chance to win and evaluate the team and its talent objectively.
I dont want to put the cart before the horse, but if we can play improved on all 3 phases (offense, defense, and special teams) to pull out wins the next two games (Atlanta looks to be more of a challenge for matchups, but the Saints wont be a cakewalk) than atleast we go 2-2 in both the first two quarters of the season. We would be 4-4 for the year (small victory is to match last years win total) and ready to face New England on a positive note.
At the half way point it gives all Fans time to evaluate objectively what this team has and has not! Just like Saban and Co. are doing!