Well since nobody else has answered, I will give you my impression of the situation, but I don't have any stats for you.
When Brady took over, it was more like everyone holding their breath. I am sure there are those who knew about him, and were fine, but most who didn't worried. The more he played and the more we won, the more relaxed things got. But once Drew was better there was a real controversy about which QB to go with. Drew had been here a long time and had a lot of supporters.
When he started he was this young stud with a great arm. And he grew into the job year after year, and we were happy. But at some point he was no longer the 'boy wonder' he was supposed to have arrived. But we still had problems in terms of winning and moving to the elite level.
It was always just out of reach and wait til next year. He still had the great arm, and the experience, but it seemed to me that most of the time he was detached from the whole situation. It was like he expected to go out and do X,Y,Z and he would and if it didn't work out, it wasn't his fault or his problem. When he couldn't make things happen on the O, it left a mess for the D, and wore them out.
It seemed that at some point he had gone from learning his job to protecting his image, and he wouldn't take any risks. He was very methodical and mechanical and wouldn't change. Now there were a few times when he played like he was on fire. When he broke his thumb, and then when he was dealing with it while healing. But those were rare, he just would never step up most of the time.
I knew for a while that there was something wrong with him, and many will talk about his not being able to move and making the wrong throw at the worst times. Indeed there are many on the board who can be very technical about his problems.
For me it was a lack of heart. I couldn't put a name to it, until Doug Flutie came back into the league. He was up in Buffalo and we would see their games, or clips on the news. Flutie wanted to win so bad that he didn't worry about looking foolish, or tarnishing his image. If it gave his team a chance he would try it.
Drew in contrast did what was expected and played it safe. I know that he has the crazy gunslinger aspect, but to me the gunslinger and playing it safe are one in the same. If he thought a QB of his stature and experience should make X throw, he would, regardless of the situation on the field, and of what the team needed. His decisions seemed to have little to do with what was going on in the game, so to many he was a gunslinger, but I always felt it was because he was afraid to take a risk and do something different from the script - even when the situation demanded it.
With Bledsoe the team wasn't one unit, it was a bunch of separate parts, and each had problems with their jobs. Some games one unit would work better than the other, and some games it worked well enough to win. But we never kept getting better, it was usually a hodge-podge.
Once Brady took over it seemed that the team became one unit and helped and complemented each other. Perhaps because they had this untried rookie and felt he needed extra help or the team wouldn't survive. But it soon became apparent that Brady could do the job, and yet the team still kept working as one. Each unit got better and they worked as one, and miracles of miracles things started to go our way.
I don't think we would have ever even won one SB with Drew, and that is sad to say.
