By Michael Hurley, CBS Boston

BOSTON (CBS) — To be completely honest, not many people expected to still be doing this in 2018. Sure, Tom Brady has stated for many years that he hopes to play through his 40s, but, well, nobody actually goes out there and does that.

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Nevertheless, here is Tom Brady, fresh off the celebration of his 41st birthday, looking fresh as lettuce, ready to assault NFL defenses for yet another year. It’s a remarkable accomplishment for Brady to even be able to make a roster at his age, but as we all know by now, Brady likes to set his bar a little bit higher than that.

So in the interest of chronicling each season for Brady, it’s only right that we start to look at the history of quarterback production at age 41 in the NFL. It’s not an extensive list, so Brady has a fairly good shot at becoming the greatest 41-year-old quarterback to ever play the game.

For those who need to be caught up, Brady has already authored the greatest season ever for a 39-year-old quarterback. Last year at 40, Brady was actually neck-and-neck with Brett Favre, before finally surpassing him with a wildly productive postseason performance.

Here’s a list at Brady’s competition at age 41:

Mark Brunell, 2011
George Blanda, 1968
Brett Favre, 2010
Doug Flutie, 2003
Warren Moon, 1997
Earl Morrall, 1975
Vinny Testaverde, 2004

As you can see, the list of those who have even tried to play quarterback at age 41 is short. Very short. Their combined output is likewise quite unimpressive.

Only three of those quarterbacks threw at least 300 passes in their age 41 seasons. Blanda and Morrall started one game apiece, while Brunell started zero. So we can politely exclude them from the exercise. Flutie only started five games, so his contributions don’t really apply here, either.

Testaverde started 15 games for Dallas, Moon started 14 games for Seattle, and Favre started 13 games for Minnesota. So, really, those are the three quarterbacks who factor in to this equation. For the sake of accuracy, Moon and Testaverde didn’t turn 41 until November of their seasons, and Favre turned 41 in early October. So in this group, only Brady is entering the season having already turned 41.

So, Brady has that working against him. But he’s got a lot more working for him.

Here’s how each quarterback fared in terms of completion percentage at age 41.

Favre: 60.6 percent (217-for-358)
Testaverde: 60 percent (297-for-495)
Moon: 59.3 percent (313-for-528)

Last year, Brady completed 66.3 percent of his 581 passes. His lowest completion percentage for any full season was 60.2 percent, way back in 2003, and his combined completion percentage over the past four years has been 65.4 percent. Brady should not have an issue putting the completion percentage feather in his cap.

Here’s how each quarterback fared in terms of passing yards at age 41.

Moon: 3,678
Testaverde: 
3,532
Favre: 2,509

Brady last year threw for a league-leading 4,577 yards. He threw for 3,554 yards the season prior … in just 12 starts. Even a significant step backward in this department shouldn’t stop Brady from surpassing that trio.

Here’s how each quarterback fared in terms of touchdown passes at age 41.

Moon: 25
Testaverde: 17
Favre: 11

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That’s a pretty impressive output for Moon, but still, Brady has thrown more than 25 or more touchdowns in every full season since 2007. (He threw exactly 25 in 2013, and of course threw zero in 2008, when he played for one half of one quarter. In 12 games in 2016, he threw 28 touchdowns.) So, while throwing 25 TDs may not be an extraordinarily high bar for Brady to reach, it’s less of a cinch than some of the other categories.

Here’s how each quarterback fared in terms of interceptions thrown at age 41.

Moon: 16
Favre: 19
Testaverde: 
20

This is quite the grisly picture, as it displays how quickly the game can speed up on a player who’s just trying to hang on. Testaverde led the league with his 20 INTs in 2004, while the other two weren’t too far off. In order to get to 16 interceptions for Brady, you’d have to combine his last three seasons. He hasn’t thrown double-digit picks since 2013. It would represent a seismic slip if Brady were to wind up throwing 10 or more picks, let alone 16 or more.

Here’s how each quarterback fared in terms of yards-per-attempt at age 41:

Testaverde: 7.1
Moon: 
7.0
Favre: 7.0

The all-important yards-per-attempt stat has seemingly taken on more meaning in recent years. When those three QBs played their age 41 season, their yards-per-attempt probably was not scrutinized all that much — the internet wasn’t quite what it was for two of the three, at least. Nevertheless, Brady is coming off a season in which he averaged 7.9 yards per attempt. For it to drop nearly a full yard, he’d have to fall off that cliff we’ve been hearing about so much. There’s been no sign of that happening just yet.

Here’s how each quarterback fared in terms of passer rating at age 41:

Moon: 83.7
Testaverde:
76.4
Favre: 69.9

All of those are below average, with Favre’s being rather dreadful. Throwing 19 picks in 13 games will have that effect. Brady last year posted a 102.8 passer rating. He hasn’t posted a passer rating below 90 since 2013. His lowest passer rating ever was 85.7 … back in 2002. He’s been over 97 since 2014 and over 102 in the past three years. Again, it would take a monumental decline for Brady to even sniff the 80s in passer rating.

And, though win-loss records are for sure not entirely indicative of the quarterback’s work, here’s the record those three quarterbacks posted:

Moon: 7-7
Favre: 
5-8
Testaverde:
5-10

Obviously, seeing Brady and the Patriots even go 8-8 would be downright shocking. This is a team that’s averaged 12 wins per year since 2001, and hasn’t lost more than four games in a season since 2009. Brady hasn’t lost 10 games in the past three years combined. So again, barring Brady losing all of his ability sometime in early October, beating Moon’s .500 win-loss record seems like an easily achievable goal.

Add it all up, and this is the bare minimum that Brady would have to do in order to become the greatest 41-year-old quarterback in NFL history:

314 completions
60.7 percent completion rate
3,679 yards
26 TDs
15 INTs
7.2 Y/A
83.8 passer rating
8-7 record

For some perspective, that would be without question the worst full season of Brady’s career. So there’s plenty of leeway for Brady to take a statistical step backward while still surpassing Favre, Testaverde, and Moon’s age 41 output.

Of course, Brady will aim for more. The incentives added to his contract in recent weeks requires him to rank in the top five among his contemporaries, not the few old fellows who managed to play at 41. But, having knocked out the age 39 and age 40 accomplishments, it feels as though Brady wouldn’t mind adding this one to the theoretical trophy closet.

All of this, of course, assumes one vital consideration: health. The risk is ever-present for any quarterback to suffer an injury, and that would seemingly apply doubly to a man over the age of 40. Brady works hard to put himself in the best position to avoid serious injury, but there’s no such thing as safety in the sport of football. An injury to Brady — either in August, September, or December — would of course threaten or derail his bid to become the greatest 41-year-old quarterback in NFL history.

But provided he stays healthy, we’ve seen enough this summer from Brady to believe that he’ll just need to continue being himself in order to claim the age 41 title. Then, most likely, it’ll be on to 42.

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You can email Michael Hurley or find him on Twitter @michaelFhurley.