I think we expect a certain level of high play from certain QBa, and Brees, Rodgers and Mahomes (2 1st round HoF locks, and a likely 3rd) would fall into that category of QB. So I think any QB beating those 3 QBs in 3 successive games culminating in a championship is a noteworthy achievement, as presumably in this case, Brady, would have to play at an elvated level for 3 succesive games against the best of the best.
It doesn't seem a stretch as a comparison.