Brady lucked out as a sixth round pick. Belichick said he had no idea Brady was such a good player (nobody else did either), and wasn’t looking for a QB. He simply thought Brady was the best available at that point in the draft.
Belichick said he traded away some of his really late round picks so he could get a second sixth round pick, because he said sometimes you get a good player in the sixth round, but almost never below it.
I thought Brady and Drew Brees would be good based on seeing them playing college.
By the time Brady was drafted there were only seven rounds as there are today. But I think into the eighties there were still 11 rounds. The 49ers drafted Dwight Clark in the 10th round and he proved to be valuable.