Tom Brady says he feels better now than when he was 25. (USATSI)
Tom Brady says he feels better now than when he was 25. (USATSI)

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Tom Brady turns 37 on August 3. He's entering his 15th year in the league, a good decade beyond the average life expectancy of your average NFL player. But the former sixth-round afterthought has made a career out of vastly exceeding expectations. So much so that he'll one day end up in the Hall of Fame, almost certainly as a first-ballot inductee.

But despite Brady's advanced age in football-playing terms, he doesn't sound like he plans to get out of the game anytime soon. He wasn't surprised -- nor does he seem to care -- that the Patriots used a second-round pick on quarterback Jimmy Garoppolo earlier this month because Brady feels better now than at any point in his career.

Yes, it sounds like something a player trying to eke out a few more eight-figure paychecks might say publicly, but it's hard not to take Brady seriously.

“You know, you don’t have to suck when you get older. It’s hard to explain this to people, but the commitment I make, in terms of keeping my body in shape and my nutrition right, should make me healthy," Brady told TheMMQB.com's Peter King recently. "I feel better today than when I was 25, and I know that’s hard for people to believe, but I do. I work at it. Basically, I work all offseason to prepare my body to not get hurt. I can’t help the team if I’m on the sidelines. I’ve got to be durable.”

But here's the thing: By Brady standards, the 2013 season was decidedly mediocre. Compared to his 12 full previous seasons (Brady only played in one game as a rookie, and one game in '08, when he suffered a knee injury in Week 1), 2013 ranked ninth in terms of passer rating, ninth in touchdown passes, and 12th in completion percentage.

That said, the Patriots went 12-4 and made their third trip to the AFC Championship Game in as many years. In fact, you could even make the case that Brady had one of his best seasons because he led New England to the postseason without a single big-time receiving threat.

To paraphrase Rick Pitino: Randy Moss and Wes Welker weren't walking through that door. Instead, Aaron Hernandez was in jail, Rob Gronkowski was recovering from various injuries, and Brady was left playing catch with undersized Julian Edelman and Danny Amendola, and inexperienced Aaron Dobson and Kenbrell Thompkins.

Another reason 2013 might be a stasticial anomaly: Brady has been much better in his 30s than he was in his 20s:

Improvements -- some drastic -- across the board. But at some point age will catch up with Brady. The only question is when.

The table below looks at quarterbacks age 37 and up who started at least eight games a season from 1984-2013 (via Pro-Football-Reference.com).

No surprise that Peyton Manning tops the list. In 2013, the 37-year-old was the NFL's best player. In fact, current and future Hall of Famers litter the top half of the table.

On average, quarterbacks at least 37 years old and starting at least eight games a season played 3.4 years, completed 59 percent of their passes with an 80.7 passer rating, and won 55 percent of the time.

Of course, quarterbacks who survive in the league until their late 30s have clearly done something right to get to that point. The average career for an NFL quarterback -- whatever their draft pedigree -- is about 4.5 years. Knowing that, it stands to reason that the old-timers still starting regularly would be playing at a relatively high level. In fact, compared to all quarterbacks age 21-36 who averaged eight starts a season from 1984-2013, the 37-and-over crowd not only held their own, they outperformed their younger counterparts.

And here's the graph above in table form:

But again, these differences are due to selection bias: The only guys left standing (sometimes literally) after age 37 are the 21 quarterbacks listed in the table several paragraphs above.

In case you're wondering: The all-time best and worst quarterbacks, 37 and older, to start at least eight games in a season.

And if you think Brady is at the stage in his life where other, non-football-related endeavors have him contemplating retirement then you'd be very, very wrong.

“There’s nothing that can wake me up at 5 o’clock in the morning on a Thursday in May like getting ready for a day of football," Brady told King. "I want to play a long time. There’s nothing I like doing that’s close to football. What’ll I do when I’m done playing? I don’t know, but I know it won’t be nearly as fun. I can tell you neither me nor Peyton [Manning] will probably be very far from the game of football when we’re done.”

The takeaway: A quick peek into the past not only suggests that Brady will continue to play at a high level in 2014, but based on what his geriatric quarterbacking counterparts have previously accomplished during their twilight years, his best football could be ahead of him.

This is great news for Robert Kraft, Bill Belichick and the Patriots. And bad news for everybody else.