Actually, they had Tampa on the ropes in the second half. Why they kicked a field goal is beyond me. Brady is a master at running out the clock.
I doubt they could have stopped Brady and the Bucs with the score tied, given that they failed to do so when they were losing. Given that it was fourth and so long, I agree with the decision. If it was fourth and short, I would go for it. Whether you do the field goal or not, you must still stop them either way, so why not do the easy field goal and then see if you can get an easier scoring chance?