Why don't you tell us how often that actually is, and while you're at it don't even try to count the '07 SB off an undefeated regular season as a Brady fail because he led a come from behind TD drive in that one only to have his defense give the lead back 2+ minutes later with 30 seconds left on the clock and 80+ yards to go. I know to you that thereafer somehow constituted epic fail on Brady's (and the OC's) part, but that's an irrational viewpoint to say the least.
Sunday Manning had just led 2 4th quarter TD drives in a matter of minutes. That actually makes it more likely he could do it again with just under 2 minnutes and a TO remaining. His 4th quarter comeback success rate like Brady's is in the roughly 60% range of opportunities. There are people trying to establish standardized comeback criteria and piece all the data together to form a historical basis for ranking QB's all time in 4th quarter comebacks. At the rate they have performed thus far, both Manning and Brady project to be among the leaders when their career's are done both by sheer volume and success rate close to double the league average.
I guarantee you since the raw data already exists, Ernie Adams has already calculated his own version of the probabilities as well as a small size sample calculation of the odds of the 2009 NE defense stopping a QB with a 60% success rate from anywhere on the field even at full strength. And he apprised Bill of those probabilities somewhere between first and third down.
Simmons is a classic case of a fan who became immediately entrenched in his own position based on the result as well as his perception of conventional wisdom thereafter using tortured logic to unearth otherwise irrelevant statistics to disprove any basis for an alternate, unconventional approach rather than attempting to understand why it had any. Had the spot been right, he'd have spent the last five days enlightening himself and smugly admonishing the dim witted stragglers of the world to join him in that enlightenment...
Pro-football-reference.com blog Quarterbacks and fourth quarter comebacks, Part II