The QB is the most important position in football. Bill could never get a competent quarterback after Brady.
Yes, I’m aware of the importance of a QB in the NFL

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He had Drew Bledsoe, in his prime, prior to Brady and was 5-14, had Testaverde in Cleveland and won a playoff game.
Had Mac who did well (Pro Bowl, 10-7) his rookie year but Belichick did a terrible job acquiring and/or keeping WR talent. Couldn’t evaluate it and didn’t want to pay for it. We all know the “brilliant” move he made in selecting Patricia as his OC for Mac.
Brady performed miracles with mediocre talent. Other franchises would grossly overvalue and over pay them only to find that their success was due to Brady (Branch, Patten, Welker, etc.). It appears CBB thought any QB could do the same but it didn’t work with Mac or anyone else.
OTOH, he at least knew the importance of the TE position. He made the decision to go with Brady after Bledsoe healed later in the year. He cultivated a healthy “next man up” attitude in NE. They had a multitude of injuries his first few years in NE and overcame them with Brady. It’s what first drew me to them - how they overcame adversity. That along with the legacies of Billy Neighbors and John Hannah.
Other than Moss for a couple of years and Gronk when he was healthy (60% of the time) Tom had mostly JAGs at NE. He made names out of WRs like Edelman, Patten, Troy Brown, Branch, Welker, Hogan, Caldwell, etc. They did little before or after their time with Brady.
Look at his OCs who were considered geniuses at NE: Weis, McDaniel. They were disasters elsewhere. O’Brien is the only one who has had any success. But most Bama fans think he is awful.