“Tom Brady has the ‘it’ factor,” said Scot Loeffler, his quarterbacks coach at the University of Michigan. “I don’t know what ‘it’ is, but he has it. He carries every intangible you’d ever want in a quarterback.” (Jim Rogash/Getty Images)

FOXBOROUGH, Mass. — More than a decade ago, before Gillette Stadium rose like a palace alongside Route 1 here, New England Patriots practice would close and the veterans would head back up the street to the cramped locker room in the base of old, embarrassing Foxboro Stadium, never home to the Super Bowl champs. A few young players lagged behind, working with position coaches, skeleton drills that amounted to the only competition of the week for those who had no chance of playing.

There, Tom Brady went to work.

“He wasn’t the Tom Brady that we all know,” said Eric Mangini, a defensive assistant on the Patriots back then.

Mangini and other assistant coaches would place “gentleman’s bets,” he said, on those post-practice sessions. Mangini, wagering on his young secondary, won his share. Tom Brady was not the Tom Brady we all know.

“He struggled,” Mangini said.

That was a dozen seasons, 300 touchdown passes, 124 wins and three Super Bowl titles ago. It is now to the point that the Tom Brady we all know seems so much of an understood commodity that he is almost an afterthought in Saturday night’s AFC divisional playoff game against Denver, the of-course-he’s-here-again star. It is now to the point that his opposite number, the Broncos’ Tim Tebow, is the nation’s cross-cultural focus. It is now to the point that when Brian Hoyer arrived in New England three seasons ago — an undrafted rookie just hoping to make the team as one of Brady’s backups — he lined up in drills and thought: “That’s Tom Brady.

“You know all the accolades,” Hoyer said, “and he’s working next to you.”

The second weekend of the 2012 NFL playoffs features an inordinate amount of star power, with four Super Bowl MVP quarterbacks — Brady, New Orleans’s Drew Brees, Green Bay’s Aaron Rodgers and the New York Giants’ Eli Manning — still playing. Tebow, of course, has at least temporarily overshadowed them all. But only one player, with a victory this weekend, can set a record for quarterbacks for the most playoff wins with one team. Only one, with a run through the playoffs to a Super Bowl title, can match Joe Montana and Terry Bradshaw as the only quarterbacks with four rings.

Only one is Tom Brady, and we all know what that means.

“Tom Brady has the ‘it’ factor,” said Scot Loeffler, his quarterbacks coach at the University of Michigan. “I don’t know what ‘it’ is, but he has it. He carries every intangible you’d ever want in a quarterback.”

Everybody believes that now. Loeffler, and a few others, believed it then. As Brady said this week, “I think everybody has a story to tell.” Brady’s is as well-known as any: part of a constant quarterback controversy at Michigan, overlooked till the sixth round of the NFL draft, thrust into the Patriots’ lineup as a second-year pro after an injury to Drew Bledsoe, now a legend. But it’s worth remembering: He wasn’t always this Tom Brady.

“Anyone who wants to say that they could see he would be as good as he is now, they’d be lying,” said Charlie Weis, New England’s offensive coordinator from 2000 to ’04. “But you knew, after that second year, this kid’s something special.”

‘Something was brewing’

When the Patriots selected Brady in the 2000 draft, he reported to camp weighing 188 pounds, and found three other quarterbacks on the roster:Bledsoe, veteran John Friesz and versatile Michael Bishop. Rarely do NFL teams keep four quarterbacks. The Patriots, that year, did.

Brady, those who were there say, spent that season remaking his body and building his mind. In many of those post-practice sessions, he took the script Bledsoe and the starters ran in practice, and ran it all again with the young skill-position players.

“He didn’t take it lightly,” said running back Kevin Faulk, the only Patriot who has been with Brady during each of his 12 seasons.

That 2000 season was the first for Coach Bill Belichick, and the noise around the team centered on Bledsoe. Quietly, though, the fourth of the Patriots’ four quarterbacks wasn’t just biding his time. The habits he has now — “He’s always looking to do more,” Hoyer said — were in place then.

“You could see that something was brewing with this kid,” said Weis, now the head coach at the University of Kansas. “Not only was his body changing, but you could see there was a nice, natural, young leader that looked like he had some moxie to him.”

Forgotten now are two things that happened that offseason, each making Brady’s rise even less probable. First, Bledsoe signed a then-record 10-year, $103 million contract. “We saw him as the franchise, the future,” said linebacker Willie McGinest, who spent 12 years with the Patriots and is now an analyst for the NFL Network. Second, the Patriots signed veteran Damon Huard to be Bledsoe’s primary backup.

Brady, though, beat out Huard, barely, for the second-string job in training camp. When Bledsoe was injured in the second game, the victim of a sheared blood vessel in his chest, Brady went in. Bledsoe never started another game as a Patriot.

Initially, Belichick altered the game plans, dialing back so Brady merely had to manage the game. But in his third start, the Patriots trailed San Diego by 10 points with less than nine minutes to go. Brady rallied the team to force overtime. On New England’s first offensive play of the extra session, he stepped to the line to see the Chargers tipping off a blitz.

“We had put in an audible for that specific blitz in that game,” Weis said. “They didn’t run it the entire game, but he saw it.”

Brady changed the play, put the ball up, drew 37 yards on a pass interference penalty, and set up the winning field goal. “You say, ‘Whoa,’ ” Weis said. “He gets it.” The Patriots won 10 of their final 12 games, swept through the playoffs, and upset St. Louis in the Super Bowl.

With these playoffs approaching, Brady hasn’t spent much time reflecting on those days. “I haven’t thought about anything about last year or last week,” he said. But he knows those roots helped get him here, to a season in which he threw for a career-high 5,235 yards, yet played, at best, fourth fiddle to Tebow, Rodgers and Brees.

“Every player who has made it this far has had to overcome some adversity,” Brady said. “There are very few people that get brought to the NFL ushered in on a red carpet.”

It might seem that way now for the Tom Brady we all know. It was not that way then.

‘As if he were fishing’

This week at Brady’s stall in the home locker room at Gillette Stadium sat the indications that his life now is not what it was then. On the floor, just below the white bathrobe with his number 12 emblazoned across the back, stood a toddler’s chair bearing the name “Benjamin,” Brady’s son with wife Gisele Bundchen, the Brazilian supermodel. Designer jeans draped his own chair.

This is the Brady we think we all know. Yet he is changing. He is 34, two years older than Brees, three years older than Eli Manning, six years older than Rodgers. Tebow said this week that Brady’s Patriots were “one of the teams that I watched over the last 12 years growing up.” With Peyton Manning having missed the entire 2011 season because of a neck injury, Brady is no longer the fair-haired boy. He is the old head, a sage.

With that comes some standing in the game. As the Washington Redskins watched film over the course of the past season, for instance, offensive coordinator Kyle Shanahan would come across tape of a defense that faced Brady and get distracted by his brilliance. He renamed Brady “The Most Interesting Man in the World,” stealing the persona of the cooler-than-thou beer pitchman on television.

“It’s his demeanor in the pocket,” said Redskins wide receiver Donte Stallworth, Brady’s teammate on the 2007 Patriots. “It’s like, for him, there’s nothing going on, not like there’s four or five or six 300-pound guys running at him trying to take his head off. He’s as calm as if he were fishing.”

Part of that calm, even back in his first year as a starter, came from preparation. “He’s a perfectionist,” said veteran wide receiver Deion Branch, though almost any Patriot could say the same thing. They don’t say it flippantly.

“We sit and work on running slants, hitches,” Branch said. “These are things that he works on, his three-step drop, making sure, ‘Hey Deion, I want you to be at six yards. I need you to be here on this slant route.’ ”

That repetition, the second-naturedness of the game, allows Brady’s mind to work through situations more quickly than most quarterbacks.

“There’s a lot of people who can get up on the board and draw up all the coverages,” said Loeffler, Brady’s position coach in college. “But he’s a guy that, when the ball hits him in the hands, he can process all that information in a very short period of time. No. 1, it’s a gift. But No. 2, it goes back to his work ethic.”

Thursday afternoon, the New England Patriots quarterback pulled on the designer jeans and wrapped himself in a black down-filled jacket. He walked from the locker room, the bulk of the preparation for his 20th playoff game already done. He is a veteran, a star, a Hall-of-Famer-to-be.

“But the thing I tell people is, if you never knew his face, then you wouldn’t know who he was,” Stallworth said. “He doesn’t give off that aura that, ‘I’m Tom Brady.’ ”

“He’s a better person than he is a player,” McGinest said.

“Being a pro quarterback that has won three Super Bowls and has married a supermodel, his life has completely changed,” Loeffler said. “But he hasn’t.”

Other than we all feel we know him, and his presence in these NFL playoffs is so expected that Tebow, Rodgers, Brees — whoever — can carry the conversation, and Tom Brady can slip quietly out the back door of the locker room, all but unnoticed as he works toward another championship.