I think you missed a big point. The EP "system" is a terminology system. The plays and routes are the same as WC, but they are identified very differently which enables the same route combinations to be run from many different formations. While there may occasionally be some new route combination invented that nobody's ever thought of before, that's rare. Josh isn't making up new pass routes.
These routes are not so much identified differently as they are packaged into one-word concepts for what happens on one half of the field, offense-wise, on the philosophy that a concept is easier to visualize or understand. Here is a great breakdown of the most
famous concept in the EP offense. You have an inside, middle, and outside receiver each of who runs a particular route according to the concept being called, no matter what the personnel or formation is.
BB's genius was to turn the EP from an
offense into a
system of concepts, i.e., everything is organized by concepts. In other words, it became
philosophically neutral. It was neither a ground or pound, air attack, or anything else, only what was required for the upcoming game, or suited to match the talent on offense (i.e., the WR group of the '07 team, or the 2 TE of the 2010's).
Concepts gives you the freedom to use any formation with any personnel group without getting bogged down in nomeclature (imagine blurting out a paragraph with the clock running out) because as long as you understood a concept, the only important thing was to know the personnel call and where you had to line up (the formation being called) and understand what the defense was giving you (man or zone, and if man, how your man was leveraged to you, which was what Brady would also see, and what Maye will hopefully someday see), hence it's moniker as the "amoeba offense." With this simple concepts system, the terminology used to identify personnel, formation, and concept all remain under 100 names for each, as opposed to the usual 500+ for a standard WC offense, and a total mathematical possibility of 60,000 variations which, as Brown points out, is beyond stupid and useless.