Yes, they DID start from scratch because McDaniels' playbook and precision timing system were too complex for Patricia and Judge to learn sans prior experience. That's where all this training camp B.S. about "simplifying the offense" came from -- it was for the coaches' sake, not the players. Mac already was a season into learning McDaniels' more cerebral approach which gave him LOS audible leeway. That arguably was his strength and got taken away because it was beyond what Patricia/Judge could accommodate.
BB put the offense fully in Patricia's hands. The only directive was implementing the Shanahan zone run-blocking scheme that didn't work out because (A) they didn't have the right OL personnel for it and (B) it turned out taking longer to master than they had time for. Patricia had his own ideas re. vertical 50-50 balls and that didn't work out either. Patricia was in WAY over his head and so was Judge as QB coach. The entire offense was slipshod from day one and never got better.
After Patricia's system was implemented there was no turning back, once the season started they had to go with it. As BB explained, changing it would require too much heavy lifting in-season. Judge was QB coach and might as well have been doing Dunkin' runs for all he could contribute.
Although a lot of this is true, there are some things that need clarification.
1. The Patriots did not scrap their entire playbook and start from scratch. They simplified the terminology, yes. They simplified the myriad of routes, yes. But it was from the same playbook Bill has been using for decades. Hunter Henry confirmed this: "it's the same playbook."
2. Bill Belichick was 100% involved in the offensive schemes. We saw it during TC, him personally working with the offense and spending more time with them than the D. This was noted by Reiss and almost every reporter out there.
3. Once the season began, Bill continued to be involved with the offense. Again, we witnessed it and it was reported as such.
4. Correct on the changes (OZB, more Vertical passes) but there was a reason for doing this. Bill realized that to compete w/ BUF, MIA, KC, CIN, he needed to get more explosive plays out of the offense. Mac was a part of this change in offensive play selection. He had input. He said so numerous times. They incorporated aspects he liked (shotgun, rpo, vertical passes, etc.). The results were not good. Too many TOs.
5. The offense production has improved recently. Still anemic but it has slowly improved. I'm still not convinced Bill moves on from Patricia. We'll have to wait and see what happens.