The meaning of the KEP is that they are dependent on a previously received Book of Abraham.
What evidence does Will produce for the direction of this dependency?
In his presentation, his significant/unique word study yielded that there are a significant number of pronouns (people, places and things) that are shared between the EA&G and the Book of Abraham. That argues strongly in favor of dependency between the two documents, but does not suggest the direction of the dependency. The debate since the Sensen papyri was gifted to the COJCOLDS and the KEP documents became public has not been whether there is a dependency or not, but the direction: (a) Book of Abraham dependent on a pre-existing EA&G, (b) EA&G dependent on a pre-existing Book of Abraham, or (c) bi-directional between them as the two documents were developed simultaneously.
Will also observed, without much detail, that the "story" of the text of the Book of Abraham is much more developed than it is in the EA&G. From this Will claims that the EA&G must be dependent on and derivative from a pre-existing Book of Abraham. The evidence however cuts against Will's observation/claim. The EA&G does not begin in the left hand column with the English pronouns, as it would if the EA&G would if it had been drawn from the English text of a pre-existing Book of Abraham. Rather, the EA&G begins with the characters in the left hand column. Then assigned to the right of some of those characters, in the next column to the right, are the phonetic sounds of such characters. In the far right column is where English text is assigned as definition to the character.
Just as each successive degree progressively expanded the English definitions for a character as compared to the prior degrees, so too did the finished Book of Abraham demonstrate another expansion as compared to those in the five degrees of the EA&G. That is, the fact that there's less 'story' in the EA&G than the Book of Abraham suggests that the EA&G came first, as work papers for Joseph Smith as he was working towards what eventually was produced as the Book of Abraham.
Will's cipher theory gives a motive why Smith and scribes might have undertaken to develop the EA&G after the Book of Abraham was already finished. His cipher theory is not evidence
that the EA&G in fact was drawn from an already completed Book of Abraham.
Rather, the evidence points to either a bi-directional dependence of the EA&G and Book of Abraham on each other as they were simultaneously being created, or that the Book of Abraham was dependent on the previously drawn up EA&G.