It seems to me his case is something like this:

Point 1: there is value of thinking of John as one of the synoptics. There are, for example, places where John is closer to two of the synopics than the third synoptic is. Often we see John retelling a story from the synoptics, but telling it more vividly by adding details like personal names (he attributes this not to John having other sources but to him simply embellishing for dramatic effect).

Point 2: There are passages where John seems to presuppose details given in the synoptics, e.g., Jn 18:11, at his arrest he chides Peter, “am I not to drink the cup the Father has given me?” This seems to refer to the cup that he had prayed only moments earlier not to have to drink–but that prayer is in the synoptics, not in John.

(This is the part I found most interesting, and I wish they had spent more time on it.)

Point 3: He thinks John is written as a sort of episodic supplement to the synoptics–interested in adding additional material, but not with retelling the whole story, because everyone already knows it. Indeed, he thinks John wasn’t just not trying to retell the whole story, but that he was very deliberately trying to give the impression that there is more to tell (see 21:25). Thus he explains the seams in John’s narrative structure (like the transition from ch.5 in Jerusalem to ch.6 when he suddenly crosses to the “other side” of the Sea of Galilee).

(For my part, I have some trouble seeing John as deliberately avoiding any overarching narrative continuity. I’ve seen collections of unordered stories that stand independent of each other, and that isn’t what John brings to mind. And if John is meant only to supplement the synoptics, not to repeat the stories that were already familiar, what of all those passages noted in Point 1 where John does exactly that, but retells them in ways that introduce contradictions? If you are writing episodic fan-fic you adhere to the details of the canonical universe where you set your story; you don’t do things like change the date of the crucifixion or move the cleansing of the temple to the opposite end of his ministry)

One more thought: Goodacre says that sequence isn’t important until the final events in Jerusalem, roughly starting at c. 13. At that point, narrative sequence becomes important. But there are the same sort of literary seams evident after that point in the gospel: e.g.,Jn 13:36, Jn 14:5, Jn 16:5, or again Jn 14:31 where Jesus says “Arise, let us go hence” and immediately launches into 3 chapters of monologue before they finally leave.

Oh, and another thought: As a former Catholic, the idea that John was presupposing the synoptics does make a lot of sense of his not having an institution narrative–despite the facts that, on the one hand, a huge section of the gospel is recounting the last supper in detail, and on the other, John seeming to have a robust Eucharistic theology (most obviously Jn 6). I don’t think it proves he knew them; there are other sources that might have been presupposed (Paul for one), or perhaps he simply didn’t think there needed to be any such narrative. A similar point could be made about his nativity–maybe he presupposes the stories of Matt or Luke, or maybe he just didn’t think he needed such a story.

Or was the final author and redactor who added John Chapter 21 implicitly claiming to have also been there from the beginning? How else can we understand the “we” statements or other commentary of the narrator

I’m not sure I understand the significance you are placing on the we passages. Could you say another word?

To be specific, what relationship do you suppose obtained between the anonymous disciple and the “we” narrator(s) who you think were themselves present from the beginning?

That is an interesting thought, but I’m not sure how to work out the details:

I have difficulty taking the beloved disciple as also one of the “we” narrators because they are spoken of in distinction in Jn 21:24.

On the other hand, if the “we” narrators were present from the beginning–themselves eyewitnesses–but distinct from the beloved disciple, why are they relying on his testimony?

I suppose it could work if we say that the “we” narrators were companions of the beloved disciple, present from the beginning. The beloved disciple wrote the core of the gospel, then (after his death?) his companions took what he wrote and added a prologue (in Jn 1) and an epilogue (Jn 21) where they vouched for the accuracy of his account.

Is something like that what you have in mind?

I meant that to be a suggestion of the coherence of the work itself (who did the author mean for the reader to understand “we” or “the beloved disciple” to refer to?), without implications for actual history (i.e., not addressing whether there ever was a “we” or a “beloved disciple” outside the pages of the fourth gospel).

So what I meant was, did the author of the fourth gospel mean to present it (perhaps as a literary deceit) as a core work written by the beloved disciple, that had then been certified and published by some anonymous group of companions who had been there from the beginning–and who in promulgating it had appended a prologue and epilogue testifying to its veracity?

Maybe the author even intended the core part of the work (the part purportedly by the beloved disciple) to read like an unfinished–replete with the sorts of literary seams and general omissions one might find in an posthumous work.

I just noticed Jn 2:1, begins “on the third day” but it is the 5th in a series of explicitly ordered days that was narrated; that seam is well known, but if you count backwards, the first day would have been the day that Andrew and an unnamed disciple started following Jesus. If the beloved disciple is indeed the unnamed disciple called with Andrew (and perhaps if the gospel was meant to be taken as the memoir of the beloved disciple, begun after a prepended prologue) the chronology fits: “On the third day (that I was following Jesus). . . “

Could it even have been a deliberate seam, left as an early hint of who was telling the story?

Why should Mark still be called a synoptic gospel when it no longer even contains the events after the resurrection found in Matthew and Luke?

They’re starting a debate over the words Synoptic and Gospel because of the invention of the Synoptic Gospel classification.

All sounds very original from European”ish” 🙄. Waste of brain cells in my opinion. European philosophy is like that after Immanuel Kant. They’re not even talking about anything or know the difference between up and down because of Relativity.