I have always believed that Bledsoe was dead man walking when Belichick got to NE , because what Belichick wanted and needed was a QB who would look at every down/ situation and make exactly the decision he would make as it unfolded. Bledsoe was never going to be that guy, but he got lucky, that is exactly what Brady knew he wanted and then did it for the next 19 years. Brady is going to enter the final trimester of his career in 2020, hopefully Belichick can find the next one between now and 2029.
Actually, in retrospect Brady was BB's choice at QB going into the 2001 season because Bledsoe was not a good fit in the offense BB was developing with Weiss. He was looking for, dare I say, a "game manager", who, as you said, would make the quick decision and throw to the right man.
Drew was a "gunslinger" in the finest sense of the term. Great arm, as tough and brave as they come. A very good QB....BUT never a fit to this offense. BTW-Aaron Rodgers or Brett Farve wouldn't have been good fits either, despite their greatness. Brady, even at the start of his career, WAS a good fit. They were looking for someone who would make the quick decision and get the ball out fast. Fortunately over time, Brady evolved beyond his original programming and beCAME the GOAT. But he wasn't that guy in 2001.
If you are honest, at that point Brady and Pennington were pretty much the same guy. Unfortunately for Chad, he got hurt and his arm got worse, while Brady's arm, conversely, seemed to get better over time, to the point that he came into the league with a medicore arm, and by the time the decade ended he was being mentioned in the same breath with all the so called "rocket armed" QB's. That isn't supposed to happen.
I feel that had Bledsoe stayed healthy and the team didn't start winning in the next few games, Bellichick would have STILL made the change to Tom by mid season.
Of course that observation comes with the retrospective of 20-20 hindsight. At the time, I, like everyone else, thought the season was over when Drew went down, and just before the Superbowl, STILL couldn't make up my mind on who should be the QB. A gimpy Brady, or a healthy Bledsoe.
All the clues were there, even before Moe Lewis, we just couldn't see them.