A TRAINING CAMP tradition now 13 years in the making, Tom Brady celebrated his birthday Friday by readying himself for a new football season.

In keeping with custom, he was serenaded aside the practice field by his fans, many of whom might've been feeling their own age in realizing that the quarterback who arrived in Foxborough at 22, and became the youngest QB ever to win a Super Bowl at 24, had just turned 35.

But even though he'd grown a year older, there's no evidence that Brady is getting old.

If last season's terrific production doesn't make that plain — he threw for 5,235 yards in the regular season, and tossed 19 touchdowns against two interceptions in the second half to finish with 39 and 12 — then consider those numbers in NFL history and how they relate to age.

Not only was his yardage the second-most in NFL history, but prior to that season none of the game's 12 most prolific seasons had come from a quarterback older than 30.

Likewise, before 2011 there had never been a quarterback beyond 30 who'd tossed more than 36 touchdowns. In fact, before Brady and the Saints' Drew Brees broke the standard last year, the quarterback's age at the time of those best-of-the-best seasons was about 28 for yardage and 27 for TDs.

That means Brady is still playing at a level traditionally reserved for elite passers seven or eight years younger. And that suggests the quarterback is still very much in his prime — with any slowdown so far not in sight.

“He works hard, day in and day out,” receiver Jabar Gaffney said. “In the film room, on the game field and on the practice field. He's a hard worker and to stay at that elite level you have to put in that hard work and he does.”

It's no coincidence that Brees defied his age at the same time as Brady. Quarterbacks today are more protected than they've ever been, which saves their bodies significant pounding, and the league has tailored its rules to help the passing game. Those advantages give QBs a greater margin for error, which could mask a slight erosion of skill.

Add that to Brady's preparedness, his intelligence, his decision-making prowess plus his ability to play through aches and pains, and there's no evidence beyond his birth year to indicate that the Patriots can't expect All-Pro-play at that position again this year — and perhaps the three or four that follow.

Brady has said he'd like to play into his 40s, and though ACL reconstruction at age 32 seemed to put those plans in jeopardy at the time, he's since quieted any concern about whether he'd return from that major surgery as the same franchise-altering player.

In three seasons since he came back, his average season has been 4,511 passing yards, 34 touchdown tosses and 10 interceptions, while completing 65.7 percent of his throws and compiling a passer rating of 104.

Viewing those numbers in grander perspective, in league history there have been only 27 seasons in which a quarterback threw for more than 4,500 yards; only 26 seasons in which a player passed for at least 34 touchdowns; and only 29 seasons in which a QB finished with a rating as high as 104.

So Brady's average post-surgery season has been on par with the most productive quarterback performances of all time. And that he achieved career bests in completions (401), attempts (611) and yards per pass (8.6) in one of the greatest statistical seasons ever — despite the absence of a true down-field receiver — the case could be made that, as he moves into his mid-30s, Brady is getting better.

If that's true, an already record-altering career could rewrite history again. In the modern NFL, the standard of success for an aged quarterback is John Elway, whose only three years with more than 25 touchdown tosses came at ages 35, 36 and 37, and whose two Super Bowl titles came at ages 37 and 38.

It had to be wild for some of the fans who sang to him Friday to think that Brady is at an age at which Elway's career was nearing its twilight, an age at which Joe Montana would never play for the 49ers again, an age at which Dan Marino became merely average.

Indeed, the quarterback is no kid anymore.

But in the modern NFL — where the stats say today's 35 may be yesterday's 28 — he sure isn't old, either.

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Brady isn't likely to play much — if at all — in Thursday night's opener, but the Pats' quarterback position may still be among the most interesting things to watch. Brian Hoyer figures to win the backup role at the start of the year, but with the veteran eligible to become a free agent at the end of the year, New England will be looking in these exhibitions to see if Ryan Mallett has progressed in his second season.

“The competition between Brian and Ryan has been pretty good,” said player personnel director Nick Caserio. “They've both had their share of good plays; they've both had their share of bad plays. I think the most important thing is to try to eliminate the number of bad plays, or mental mistakes, or whatever it may be.”

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Prior to their preseason clash, the Patriots and Saints will practice together on both Tuesday and Wednesday — and some different colors should be a welcome sight for the Patriots, who were as a team forced to run three laps on Friday after fights interrupted practice for the second time in three days.

It should also present New England's work-in-progress secondary some valuable reps against Brees and New Orleans' diverse cadre of receiving threats.

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Dave D'Onofrio covers the Patriots for the New Hampshire Union Leader and Sunday News. His e-mail address is ddonof13@gmail.com