Legacy Damage
The problem for Belichick is that every time the Patriots lose a game, it damages Belichick’s short-term legacy. There will be increasing numbers of people calling for him to retire or even for Robert Kraft to pull the trigger. He deserves time and respect because of his impact on the sport (via Sportskeeda).
But memories are short and the NFL is a cutthroat business. Nobody wants to see him lose his job but perhaps the best thing for him to do is announce that this is his final season. Then the players may pour their hearts out for him and recognize they’re also playing for their jobs under a new head coach.