Tom Brady, QB of the New England Patriots, addresses the media at Super Bowl XLIX Media Day Fueled by Gatorade inside U.S. Airways Center on Jan. 27, 2015, in Phoenix. Rob Carr/Getty Images

New England Patriots quarterback Tom Brady secured his place as one of the NFL’s all-time great quarterbacks more than a decade ago. By age 27, the former sixth-round draft pick had already become the NFL’s quintessential “rags to riches” story, with three Super Bowl titles, a pair of Super Bowl Most Valuable Player awards and the off-field endorsement deals that go with them.

And yet, in a twist of football fate, Brady and the Patriots’ status as perennial contenders has not translated into additional Super Bowl success. Brady lost both of his Super Bowl appearances since 2007. Now 37, Brady’s latest – and possibly final – Super Bowl game, against the Seattle Seahawks on Sunday, will occur under the specter of unanswered questions regarding his alleged participation in the Patriots’ “Deflategate” scandal. For critics, Brady needs a win to cement both his on-field legacy and his long-term business brand.

“You want to be remembered for positive things – for achievement, for excellence, for discipline,” said Tim Calkins, a marketing professor at Northwestern University’s Kellogg School of Management in Illinois. “I think for Tom Brady, the importance of the Super Bowl has gone up dramatically, because if he wins, he can put a lot of this behind him and he can ensure that his brand is very well entrenched. If they lose, he’s going to miss that opportunity.”

The Patriots have been accused of deliberate attempts to gain an unfair competitive edge before. The NFL stripped the Patriots of a first-round draft pick and fined head coach Bill Belichick an unprecedented $500,000 in 2008 after the league found New England guilty of secretly videotaping an opposing team’s defensive signals. “Spygate” caused irreparable damage to Belichick’s legacy, with critics noting as recently as this month that the Patriots had not won a Super Bowl since the videotape scandal was uncovered.

Brady’s legacy and brand escaped “Spygate” mostly unscathed, aside from general associations given his proximity to Belichick. “Deflategate” is different – Brady is at the center of the NFL’s ongoing bid to determine how 11 of the 12 game balls the Patriots supplied for use in the 2015 AFC Championship game on Jan. 18 were inflated below league standards. Brady categorically denied any wrongdoing during a lengthy Jan. 22 press conference.

“I feel like I have always played within the rules,” Brady said, according to ESPN. “I would never break the rules.”

But detractors questioned Brady’s claim of innocence, particularly after several retired NFL quarterbacks admitted game ball alteration was a routine occurrence within the league. Speculation on the potential impact to Brady’s brand began almost immediately. ESPN’s Sal Paolantonio suggested Brady’s denials were merely an attempt to counteract damage to his image in light of his partnership with Ugg boots.

“Women don’t like cheaters. And what’s the nNo. 1 demographic that Tom Brady tries to sell Ugg boots to? Women,” Paolantonio said. “This was clearly motivated because Tom Brady knows, and the people around him know, that his brand is damaged by this -- not only on the football field but also what he sells off the football field.”

Brady’s contemporaries have also expressed suspicion about his story. Former St. Louis Rams quarterback Kurt Warner, who lost to the Patriots on a last-second field goal in Super Bowl XXXVI, said he now has a “sliver of doubt” as to whether New England did something to gain an unfair advantage during their victory. New York Giants quarterback Eli Manning, who has twice defeated Brady-led teams in the Super Bowl, said it “seemed kind of strange” that Brady knew so much about ball pressure amid "Deflategate."

The “Deflategate” scandal only compounds nearly a decade’s worth of criticism Brady has faced during his Super Bowl drought. The questions began after Super Bowl XLII in 2007, when the Brady-led 16-0 Patriots lost the title game and an undefeated season to the Giants. Four years later, the Patriots returned to the Super Bowl only to lose to the Giants once again. The 2012 and 2013 NFL seasons featured back-to-back Patriot losses in the AFC Championship game. Suddenly, the three-time champion couldn’t win the big game.

Yet critics who point out Brady’s recent failings in the playoffs also fail to note the historic nature of his career accomplishments. Aside from his three Super Bowl rings, Brady is a two-time NFL MVP, a two-time NFL offensive player of the year, and the league’s all-time leader in postseason passing yards and touchdowns.

As of this year, his six Super Bowl appearances are more than any other quarterback in NFL history. A win would allow Brady to join immortals Terry Bradshaw and Joe Montana as the only quarterbacks ever to win four Super Bowls. But regardless of whether he wins or loses against the Seahawks, Brady’s on-field résumé is virtually unassailable.

“I don’t think whether he wins on Sunday or not has any impact at all. Once you’re a champion, it’s kind of like being president of the United States. That title never goes away,” said Joe Favorito, a longtime strategic communications professional and instructor at Columbia University in New York City.

Away from the gridiron, Brady has teamed with his supermodel wife, Giselle Bundchen, to build a formidable marketing brand. A sought-after ambassador for high-end products, Brady has held deals with Ugg boots, Movado watches, Glaceau Smartwater and Under Armour. Brady earned $7 million through his off-field endeavors in the past year, second only among NFL players to fellow future Hall of Fame quarterback Peyton Manning. A loss in Super Bowl XLIX won’t slow Brady’s brand or prevent him from branching out into broadcasting, experts said.

“As soon as he retires, every network will want him. He will probably take a number of additional endorsement deals. I’d rank him, if he retired after the game on Sunday, as one of the top five guys I’d want as a brand ambassador,” said Darren Marshall, executive vice president at sports marketing agency rEvolution.

A specific number of Super Bowl victories isn’t a prerequisite for long-term marketing success. Former Miami Dolphins quarterback Dan Marino finished his career in 1999 as one of the most statistically prolific players in NFL history, but he never won a championship. Still, he has enjoyed a successful post-NFL career as a CBS broadcaster and television pitchman.

Manning is another example. At age 38, the Denver Broncos quarterback has thrown more touchdown passes than anyone in NFL history, but he has just one Super Bowl ring, compared to Brady’s three. That hasn’t stopped him from becoming the league’s highest-earning endorser, with high-profile deals worth $12 million away from the field.

From a marketing perspective, Brady’s combination of good looks, boy-next-door charm and championship success could allow him to completely surpass his peers.

“When it’s all said and done, he might be one of the most marketable athletes because of his stature. Handsome guy, he’s got the supermodel wife, he’s been on America’s team when you think about the Patriots. He’s one of the most marketable guys you could ever come across. I think a guy like Terry Bradshaw or Joe Montana and even Peyton Manning, they’re more like the everyday guy. But Brady’s more of an elite brand,” said Tom O’Grady, chief creative officer at sports marketing agency Gameplan Creative.

The only obstacle to the long-term success of Brady’s brand is the outcome of the NFL’s investigation into Deflategate, experts said. Definitive proof that Brady had direct knowledge of deliberate attempts to gain an unfair competitive edge would negatively affect his “squeaky-clean” public persona. Fans wouldn’t care so much about the act of deflating a few footballs as the fact that Brady lied.

“If there is some kind of smoking gun, some ballboy comes out and says, 'Tom Brady told me to do it,'” which means then that he lied, then I think you’re into Pete Rose territory. In sports, it usually isn’t the act [that does damage], it’s the cover-up,” Marshall said, referring to the Cincinnati Reds legend who denied for years that he gambled on baseball, only to admit in 2004 that he actually did.

But even then, the NFL would require damning, unprecedented proof of Brady’s complicity – something egregious enough to make the Patriots quarterback a direct target for public outrage. That doesn’t seem likely, O’Grady said.

“I think short of him standing on the sideline with a Gatorade towel deflating the ball, I don’t think he’ll get his hands that dirty on it,” he said.