Well, ask a Steelers fan. We are Patriots fans so every little thing Brady does is magic...I am sure Steelers fans would call the 2005 playoffs a series of "signature wins." To be the top 3 seeds (Cincy, Indy, and Denver) on the road and then win the SB is pretty amazing. Even Seattle was the #1 seed out of the NFC.
How about in 2008 when they beat a hot Chargers team or defended their home turf in the AFCCG against their archrival (Baltimore) enroute to another SB? If the Pats had not pissed away the Jets game, we would have called that a "signature" win for the ongoing dynasty.