Aaah, yes. His struggles were all because of the elbow injury. Got it.
They were 8-0 because the defense was putting up absurd numbers in terms of turnovers and defensive points scored, against a week opening schedule. In addition to defensive points scored, all year long Brady and the offense benefited from short fields, due to the defense pinning teams close to their own goal line, along with forced turnovers.
The defense and weak schedule that carried the Patriots to 11-5 in 2019 were both a distant memory last year.
You are trying to rewrite history. You are forgetting that the offense was so anemic (not 2020 anemic but bad nonetheless) that Brady was being asked whether he would be content with being a “game manager”, as long as the Patriots went on to win another championship. Of course, he refused to answer that question, which says a lot about his 2019 attitude.