How much longer can Tom Brady keep being Tom Brady?

In 2017, Tom Brady set the NFL record as the oldest player to ever start a Super Bowl at age 39.

In 2018, Tom Brady broke his own record by starting Super Bowl 52 at age 40.

On Sunday, he’ll rewrote the record books again, taking the field at Super Bowl 53 at 41 years old — more than 17 years older than the Rams quarterback who’ll challenge him, Jared Goff. And while he threw an interception on his first pass and failed to find the end zone even once, he still walked away with his sixth NFL title — setting the league record in the process.

So will 2019 mark his last hurrah? According to the man himself, there’s “zero” chance that’ll happen.

Brady remains steadfast in his quest to play until he’s 45 years old — a goal that would make him the oldest starting quarterback in league history. Only eight players have celebrated their 45th birthdays as part of an NFL roster. Two of those came back in the 1920s, when football was a lawless wasteland and players were paid in skirt steaks. After 1925, all six of those remaining elders were all primarily kickers — though George Blanda still threw some passes as the Raiders’ third-string quarterback and played until he was 48.

According to Pro Football Reference, 2,414 players have thrown a pass in the NFL between 1920 and 2018 — 892 of them primarily played quarterback. Only 19 have ever thrown a pass at age 40 or later. Brady came into the league with a roughly 2 percent chance of playing QB until his fifth decade. He turned those slim odds into a pair of post-40 Super Bowl appearances while becoming the most prolific older quarterback in league history:

*John Nesser also played into his 40s in the 1920s, but none of his statistics are recorded on Pro Football Reference, so he’s been excluded from the list.

Brady may not break Blanda’s record of being the oldest player to throw a pass in the league, but he’s already thrown more passes at age 40 or older than any player in history. If he plays in 2019 — which again, will happen according to the veteran himself — he’ll set the record for highest percentage of career passes thrown at age 40 or older. He’s won more playoff games than any starting QB aged 40 or older has, and if he wins Super Bowl 53 he’ll erase his own record as the oldest starter in NFL history to ever raise the Vince Lombardi Trophy.

It’s clear Brady has been a massive outlier in terms of quarterbacks. But now the question becomes — can he keep it up?

His post-40-years-old career numbers say yes.

Brady told former teammate Willie McGinest that he’ll retire when he starts to “suck”:

So far, that hasn’t happened.

At this point, Brady’s peer group consists mostly of backup passers, spot starters, and players who gave up their active roles before turning 42. Unsurprisingly, his numbers over the past two seasons leave that group far in his rear view.

Brady’s 100.2 passer rating since turning 40 is better than his career average of 97.6. It would rank third in NFL history among all quarterbacks — only Russell Wilson and Aaron Rodgers have better career ratings.

That gives hope to Brady’s foray into uncharted waters, though those numbers are sure to decline. The 41-year-old took a step backward in 2018, both statistically and on the field, during the regular season.

The good news for the Patriots is his numbers roughly fell back to his mid- to late-30s level of performance — five years during which he never missed an AFC title game. While he fell to the middle of the quarterback pack and failed to crack the top 10 in passing yards per game, touchdown rate, adjusted yards per pass, or quarterback rating, he still led New England to another AFC East title, another AFC Championship, and another Super Bowl win.

So what comes next?

There aren’t really any good predictors for Brady’s age 42 season. Only three other quarterbacks — Moon, Testaverde, and Flutie — have seen extended snaps at that age. They combined for five appearances and two starts. Flutie outperformed expectations in a 199-yard, one-touchdown performance to beat the Chiefs in 2005. Testaverde threw a typical amount of interceptions in mop-up duty with the 2005 Jets. Moon was slightly below his career average in 1998 when he turned 42 at the tail end of 10 starts for the 8-8 Seahawks.

The best analogue for Brady may be Favre, but even that’s a stretch. The Hall of Famer started 29 games after turning 40, buoying a talented Vikings team in the process. But he was an unpredictable presence after leaving Green Bay, leading the NFL in interceptions one year and then holding the league’s lowest interception rate the next.

He sandwiched two bad seasons around a great one in which he led the Vikings to within one interception of Super Bowl XLIV. His quarterback rating went from 81.0 at age 39 to a career-high 107.2 the following year before bottoming out to a career-low 69.9 in his final season as a pro.

Brady hasn’t had these kind of wild swings. Even if 2018 marked what may be the start of his descent down a late-career bell curve, he still managed to play roughly as well as he has throughout his legendary tenure in New England. That’s a little concerning in a season where elite passing offenses dominated the league, but it’s still a solid body of work. It also could have been a product of his limited receiving corps; Rob Gronkowski had a down year as potential retirement looms, and Julian Edelman and Josh Gordon combined for only 23 games this fall.

The Patriots can handle diminishing returns from their star (and ancient) quarterback by insulating him from Favre-ian swings. That means retaining the core of an offensive line that’s kept him from being sacked (though left tackle Trent Brown could leave for a massive contract in free agency in favor of 2018 first-round pick Isaiah Wynn). It also means creating a contingency plan for Gronk’s eventual departure and restocking a receiving corps with uneven returns after Edelman.

The franchise’s history suggests it will turn to a combination of under-the-radar free agents, draft picks, and holdovers to back up Brady in 2019. That’s worked fine in the past. The question now is whether a 42-year-old Brady can turn another roster of undervalued acquisitions and late-round gems into a starring cast — or whether another year of football will have dulled his senses just enough to make the Patriots mortal again.

Brady’s performance in 2018 suggests the latter. And history? Well, history doesn’t really know, since Brady is pretty much unprecedented.