That is not true.
For example, there was one clear cut play in preseason vs. Bengals on Moss's second TD where he was initially on an inside slant but after seeing the CB identify that play and anticipate it by shifting his weight inward, Moss, when he reached the apex of the route where he would turn inside, faked half a step inside and took off on the outside. Brady was in tune with all that, he had identified this pre-tendency in the playcalling and was ready for anything if it had happened (if X, then Y). This is a great example of sight-adjustment.
The degree of difficulty in regard to learning the Patriots offense is not the play tree itself but the modifications that go with it that form the branches which form into further branches, and those modifications are formed on tendencies, projections predicated on the post-snap look that the defense reveals, as well as the game plan, or player tendencies (again, the if X then Y). It is also sometimes sight-adjusted on defensive shifts- which is why even someone as Aiken can have trouble, even though he's been in the system for quite a while now. He ran the correct route, modification (inside slant off 3 drop) but failed to identify that the D was in man coverage, which is why he stalled right after the slant and the ball went ahead of him.
The key to understanding this is that just as the defense can morph into anything to beat whatever is needed for a particular week, so does the offense morph to equal depth. This is BB's philosophy, he does NOT stick to one particular offense (e.g., Pittsburgh "this is what we do, see if you can beat us").
But at the same time BB knows that overcomplicating the play tree serves nothing.. (that is what I believe is his true genius).
So what does he do? (and this is the base of the modified Erhardt-Perkins stuff he runs). He begins with a number of base plays that are not themselves complicated, but then when you modify it by formation, then set (e.g., 1 RB in motion on 3 wide and 1 TE) then individual route modification, then tendency, then all the adjustments (sight, defense, coverage tendencies) it gets pretty close to info overload. That is the "genius" of the Erhardt-Perkins system and also its drawback when you come to it from another system. The EP system is name based, so you would go something like "Baker" (base formation) "Yell" (adjusted formation: 1 RB to motion, 3 wide/1 TE) "twenty" (base play that comes out of the adjusted formation) "barrel" (individual route) "light" (adjustment).
So you will hear Brady say "baker yell twenty barrel light (and add a tendency option or two)."
This probably is an oxymoron that it sounds complicated, but it is not, as long as you don't lose sight of the play tree, and remember to think in terms of simple things first, then complicated, second.
Now when you come from another system, especially one that is number based, for example, let's say you have a 3 wide, you can just say "924 hook fly" where the x runs a 9 (let's say deep out) Y runs 2 (inside slant) and X runs 4 (curl) hook fly could be an option depending on what's happening in the flat or if the safeties cheat down or play zone.
Simple enough in itself, but when you shift from a numbers system to a name oriented one, it's like being forced to learn chinese in a week, if you get traded.
And on top of that, while Brady is not opposed to sight adjustments, he still likes his receivers to run precise routes with great timing so he can throw the ball before they get there. Remember that is Brady's greatest ability.. his accuracy and his ability to get rid of the ball so fast.
