It has been a age long question of whether a coach is the most important or a QB. Especially in the situation of New England, between Brady and Belichick. Well this year was the first year they were apart, and there were two drastic finishes.
They are considered the best in their positions to ever be around, and this year was the first year that New England missed the playoffs since a Brady knee injurie. In fact the Brady less patriots looked horrible, they were under under 500 for the first time I believe under Belichick. So there was a huge decline, and granted it was only one year but seems to be you need a quarterback.
Brady on the other hand went to Tampa, and it was a struggle for a bit. But, guess what... He won another Super Bowl ring, and got a team that was below .500 to 13-3. Huge difference a good QB can make.
So if you are faced with the ability to build a team, it looks as if you should spend your money on a QB. They are definitely going to win you more games then a coach will.