I'm in total agreement with your OP except for this. I'm not sure play calling is even the issue at this point. The biggest problem offensively is guard play. The team simply can't run the ball consistently & there are major struggles in pass pro right now.

When you can't run the ball effectively on early downs, it sets you up for 3rd & longs. That's where the other problem of not being able to protect Brees comes into play. Both problems lead to predictably in the play calling especially on 3rd down. It also causes defenses to have no fear of the running game to a point where defenders are less prone to bite on play action. This causes the offense to lose the ability to move safeties & MLB with run fakes. It's why the offense can't attack the seams right now which has been a staple of the offense since Payton arrived.

If 3rd downs are manageable, the threat of the run or pass is still there but having to convert long distances constantly basically eliminates the threat of the run. DC's can then bring extra defenders & pass rushers can pin their ears back without fear of having to defend the run. It's all a trickle down effect of bad interior line play.

Not only that but the immediate pressure Brees gets most times causes him to move off his "spot" & he has to reset which effects his timing with the receivers. Last season & in the first 2 games this year, he has had to move around more than I can ever recall. If a team can't block upfront consistently it will effect the entire offense. It's just that simple.

Go back & look at how inconsistent the offense was early in 2011. That was the greatest offensive season under Payton yet Olin Kruetz was terrible at center the first half of the season. The team was only 5-3 at the midway point in the season. Payton put DLP at center to shore up the position & the team went 8-0 the rest of the way. This team doesn't seem to have legitimate options currently on the roster to replace both Evans & Lelito though.