I suppose, who's the replacement? If you can replace Belichick with someone like Sean Payton then fine. Things have unraveled badly for Belichick over the last few seasons. Start with he let the GOAT go and heading into the 4th season post-Brady we still don't know if we have an adequate replacement. Not based on the 25-26 record with 0 playoff wins. Meanwhile the guy he pushed out the door is 5-1 in the postseason with a Super Bowl championship and heading into his third straight postseason.
Bringing in a completely washed up Cam Newton in 2020 was a really bad look. The offense was a complete joke.
His 1st round quarterback looked promising in 2021 until he effectively benched him in the wind storm at Buffalo. Since then Mac has been a completely different quarterback.
Pre-wind storm game:
Post-wind storm game:
Then there's the Patricia/Judge debacle. Two failed head coaches, who got extremely poor results from their quarterbacks, with no offensive coaching experience, hired to design a new offensive system and takeover the development of your franchise quarterback. This spectacularly blew up in Belichick's face. And probably will be the determining factor if he's to return for the 2023 season. Is Belichick willing to replace his unqualified buddies with a known experienced and competent offensive coordinator? If not then he should be shown the door with them.
What you laid out has been my biggest issue with Bill. The complete lack of planning for the future. Shoved the face of the franchise out the door with absolutely zero succession plan at the most important position on the team. Bill was apparently content going into the season with Stidham (until he went to a wedding or something) and Brian Hoyer only to pick up a broken down Cam Newton because he was cheap. That season for some inexplicable reason decided to franchise a guard for $14 million costing us a likely 3rd round comp pick. Didn't maximize value with Stephon Gilmore and then he tore his quad and we traded him the following season for pennies on the dollar. He also refused to pull Cam down the stretch when we were out of it and get a look at some of the younger guys on the roster so we could have a chance in some meaningless games.
Then in 2021 he goes on a spending spree and the only one who has lived up to his deal is Judon. Some of the other deals are major cap hinderances for underperforming players. Then like you mentioned something seemed to change in the way the staff managed the gameplay's with Mac and his performance slipped.
2022 to me is his most egregious year outside of letting Brady walk in 2020. Bill couldn't have bungled the offensive coaching staff and hardly unless he deliberately tried. This goes back to the whole lack of planning theme of late. Josh has been rumored to leave every single year for the last 6 or 7 and yet he didn't seem to groom anyone to take over. Bill just put all his eggs in the Josh basket until that basket went to Vegas and Bill made arguably one of the most ridiculous decisions of his career in letting a former defensive coach call plays as an OC to predictable results.
I worry that Bill has been trying to band aid the situation together to win 8-10 games and be a middling team instead of ripping the bandaid off and rebuilding like he should have in year one without Brady. He had plenty of excuses in 2020 with Covid and all the opt outs but instead he wanted to re-sign McCourty and Slater, franchise Thuney and sign a veteran QB to keep us right in the middle and get a few wins closer to Shula. Last year he tried to buy his way out of the hole he created and ultimately it didn't work in the long run but got Bill 10 more wins.