THE PROBLEM WITH living your life under the spotlight is that the camera captures only the public eruption, not the months of silent anger. On Dec. 3, when the New England Patriots played the Buffalo Bills, Tom Brady walked to the sideline after throwing late and behind receiver Brandin Cooks on third down, ending a first-quarter drive. Brady was angrier and more irritable than usual, as has often been the case this season in the eyes of some Patriots players and staff. As he unsnapped his chinstrap, Brady passed offensive coordinator Josh McDaniels on the sideline.

"He was wide open," McDaniels said to Brady, referring to Cooks.

Statements From Patriots, Don Yee The Patriots issued a joint statement from Chairman/CEO Robert Kraft, coach Bill Belichick and quarterback Tom Brady after the ESPN.com story was published: "For the past 18 years, the three of us have enjoyed a very good and productive working relationship. In recent days, there have been multiple media reports that have speculated theories that are unsubstantiated, highly exaggerated or flat out inaccurate. The three of us share a common goal. We look forward to the enormous challenge of competing in the postseason and the opportunity to work together in the future, just as we have for the past 18 years. It is unfortunate that there is even a need for us to respond to these fallacies. As our actions have shown, we stand united." Statement from Brady's agent Don Yee: "I don't really know what to say; it's tough to have a response since it didn't appear to me to have one on-the-record quote. All I can suggest is don't believe everything you read."

Brady kept walking, and glaring at McDaniels, so the coach repeated: "We had him open."

Brady snapped, pivoting to McDaniels and yelling at him, "I got it!" Everyone within earshot, including head coach Bill Belichick, turned to watch as Brady screamed. He removed his helmet, and as a Patriots staffer held him back -- and with McDaniels' father and legendary high school coach in Ohio, Thom, in the stands behind the bench -- capped off the exchange by yelling, "F--- you!"

Video of the scene went viral, with many rationalizing it as a symptom of Brady's legendary competitiveness. Brady would later apologize to McDaniels, who dismissed the incident to reporters as "part of what makes him great." After all, many in the Patriots' building knew that Brady's explosion wasn't really about McDaniels. It wasn't about Cooks. And it wasn't about the Bills game. It was about the culmination of months of significant behind-the-scenes frustrations. For almost two decades, Belichick has managed to subvert the egos of his best player, his boss and himself for the good of the team, yielding historic results. This year, though, the dynamics have been different.

THE PATRIOTS ARE in uncharted territory. They haven't just won games and titles. They've won at an unprecedented rate and over an unprecedented span, which makes the feelings of entitlement creeping inside Gillette Stadium unprecedented as well. The Patriots, in the only statement anyone associated with the team would make on the record for this story, responded to specific questions by saying that there are "several inaccuracies and multiple examples given that absolutely did not occur," though they declined to go into detail. But according to interviews with more than a dozen New England staffers, executives, players and league sources with knowledge of the team's inner workings, the three most powerful people in the franchise -- Belichick, Brady and owner Robert Kraft -- have had serious disagreements. They differ on Brady's trainer, body coach and business partner Alex Guerrero; over the team's long-term plans at quarterback; over Belichick's bracing coaching style; and most of all, over who will be the last man standing. Those interviewed describe a palpable sense in the building that this might be the last year together for this group.

Brady, Belichick and Kraft have raised expectations and possibilities so high that virtually no other team in the Super Bowl era could truly comprehend what it's like to be them. Brady and Belichick weren't only pushing the boundaries of what a team could accomplish. They also were challenging basic understandings of how a group of high achievers escape the usual pulls of ego and pride. For 17 years, the Patriots have withstood everything the NFL and opponents could throw their way, knowing that if they were united, nobody could touch them. Now they're threatening to come undone the only way possible: from within.

Brady's body coach and business partner, Alex Guerrero, has found a spot in the quarterback's famously small group of advisers. He persuaded Brady to find the time to establish the TB12 Method. Elsa/Getty Images

THE CRACKS FIRST revealed themselves in early September. The season had just started, and Guerrero was once again becoming an issue in the Patriots' building, just weeks before the release of Brady's first real book, "The TB12 Method." It was more than a fitness and diet guide. For Brady, a self-described "loner" who always seemed most comfortable surrounded by family or on a football field, the book represented a move to extend his brand beyond the game -- and beyond the Patriots. Until a few years ago, he seemed uninterested in ever doing so, content to be a father and husband and son and brother and transcendent quarterback, knowing there wasn't time for much else.

Guerrero persuaded Brady to find time. The two men had worked together for years, with Guerrero having found a spot in Brady's famously small group of advisers, eventually becoming a godfather to one of his sons. Guerrero has a history of controversial methods -- in 2005, he paid a judgment to the Federal Trade Commission to settle allegations that he had claimed dietary supplements could help cure cancer -- and he believed he had discovered a way to revolutionize how athletes train. In his book and in the building, Brady was offering opinions not only on training but also on lifestyle, writing that he envisioned a world populated with TB12 Sports Therapy Center franchises.

Few in the building had a problem with Brady's method -- mostly based on stretching with bands, eating lots of vegetables, drinking lots of water, getting lots of sleep and, most of all, achieving peak "pliability." They did have a problem with what Brady and Guerrero promised the TB12 Method could do. They claimed it could absolve football of responsibility for injury: "When athletes get injured, they shouldn't blame their sport," Brady wrote. The method also was so consuming and unwavering in its rules and convictions that, while it helped some players, it felt "like a cult" to others, one Patriots staffer says. The way TB12 began to creep into Brady's life worried people close to the QB, many of whom were suspicious of Guerrero. "Tom changed," says a friend of Brady's. "That's where a lot of these problems started."

Brady and Guerrero's training beliefs introduced an unspoken pressure in the building, with players wondering where they should work out. In August, receiver Julian Edelman blew out his knee, costing him the season, and there was "hypersensitivity" among players, in the words of a Patriots coach, over who would take his place. New players felt the surest way to earn Brady's trust was to join Rob Gronkowski, Danny Amendola and others by seeking advice from Guerrero at his TB12 clinic -- and not team doctors, which Belichick preferred. Guerrero says he wasn't pressuring players to adopt his approach. "Players have always decided to come or not come on their own," he says now. But according to multiple sources, players openly discussed with Patriots coaches, staff and trusted advisers whether to follow Brady or the team, leaving them trapped: Do we risk alienating the NFL's most powerful coach or risk alienating the NFL's most powerful quarterback?

EARLY THIS SEASON, Belichick wanted to discuss all these issues with Brady.

Guerrero had been around the team for years, mostly as an unthreatening outsider who worked with former linebacker Willie McGinest and, starting in 2004, Brady. On the author page in his 2004 book, "In Balance for Life," Guerrero says he received a degree in traditional Chinese medicine from the now-closed Samra University of Oriental Medicine in Los Angeles, and later opened a sports injury, rehabilitation and performance-enhancement center, also in Los Angeles. In 2013, Belichick had welcomed Guerrero into the New England fold, giving him free rein in the building and, sources with direct knowledge of the situation say, access to meetings in which medical records for Patriots players were discussed (Guerrero denies ever having seen any records). The coach figured that, because Guerrero had Brady's best interests in mind, he probably had the Patriots' best interests in mind too, and could be trusted. But Guerrero often would blame Patriots trainers for injuries, while offering few insightful opinions of his own, and Belichick quickly realized inviting him had been a mistake. And so in 2014, he eliminated Guerrero's access to those meetings while keeping him on as a team consultant. That was the same year Brady and Guerrero decided to market their business as revolutionary; the same year that Brady began to speak unwaveringly about playing into his mid-40s; and the same year that Belichick drafted Jimmy Garoppolo out of Eastern Illinois -- the first sign that Belichick was invested in a future that did not include the quarterback who had changed his life and legacy.

It was also the same year that the Patriots would go on a run toward their fourth Super Bowl win, altering the team dynamic in fundamental ways that would come to a head this fall. During their 10-year championship drought, Brady and Belichick had come up just short together and could only dive back into the redemptive power of work, trying to slim the margins between defeat and victory. In beating the Seattle Seahawks in Super Bowl XLIX, the two men drew strength from different touchstones. Belichick found virtue in his idea of the Patriot Way -- the demanding, football-first culture with an emotionless pursuit of victory -- and Brady found virtue in his Method, which he believed helped him thwart the inevitability of time, reinforcing his belief that he was still not on the downside of his career and deserving of a new contract. In 2016, Kraft and Brady's agent, Don Yee, began negotiating a new deal; Belichick and other Patriots staff had to abruptly leave the NFL combine in Indianapolis to be part of the process. Brady's two-year contract, with a $28 million signing bonus, was designed to set up 2018 as a key year, when the team could, in theory, look at a 41-year-old Brady and his $22 million cap hit and decide if it made sense to transition to Garoppolo.

A year later, after another Super Bowl win -- the Brady-led, historic comeback from 28-3 to defeat the Atlanta Falcons -- Brady's stature in the organization had grown to the point that he was considered management. New players often address him as "sir." As Brady gained power, so did Guerrero, who became an even more divisive force in the building. One player visited TB12 under what he perceived as pressure, and declined to allow Guerrero to massage his injured legs. Instead he asked to keep treatment limited to only his arm, out of fear that one of Guerrero's famous deep-force muscle treatments would set back his recovery. The Boston Sports Journal would report on another player who was told by Patriots trainers to do squats but later instructed by Guerrero to not do them. Brady would tell teammates, "Bill's answer to everything is to lift more weights" -- a claim that many staffers and players felt was unfair, given the team's dedication to soft-tissue science and a healthy diet.

And so after several such incidents, Belichick explained to Brady in early September that many younger players felt pressured to train at TB12 rather than with the team, and asked the quarterback what was going on. Brady said he didn't know anything about any such pressure, according to people briefed on the exchange, and the two men left the meeting without any resolution.

Belichick felt the need to permanently clarify Guerrero's role, drawing sharp boundaries. After the brief discussion with Brady, Belichick emailed Guerrero to let him know that while he was welcome to work with any players who sought out TB12, he was no longer permitted access to the sideline or all of the team headquarters because he wasn't an employee of the Patriots (a point that Belichick would resoundingly make clear when reporters asked about Guerrero).

An email designed to solve problems only created more of them. Guerrero texted some of the Patriots players who were clients and specified, he says now, "that I would need to treat them at the TB12 Sports Therapy Center." But several players told staffers and coaches that Guerrero gave them the impression that Belichick would no longer allow them to work with him. In the view of many Patriots, it was an example of Guerrero trying to split the organization by turning players against Belichick. All of this happened as Brady, serving as TB12's test case, continued to reiterate publicly and privately his goal of playing into his mid-40s. In October, he again explained to Kraft and Belichick his plans to play a few more years. The question was whether Brady had earned long-term security from the Patriots, or if he would finish his career somewhere else.

Belichick drafted Jimmy Garoppolo in 2014 as a future successor to Brady but traded him to San Francisco this season under orders from Patriots owner Robert Kraft. Roy K. Miller/Icon Sportswire

BELICHICK HAS FAMOUSLY staked his entire career on the idea that long-term security doesn't exist in the NFL. Fear, paranoia, the irrelevance of yesterday and tomorrow, and acceptance of Belichick as the ultimate authority are as much a part of the Patriot Way as selflessness and sacrifice. For years, Brady stood as the perfect model for Belichick's system, a future Hall of Famer who could withstand tough and biting coaching. Brady always knew the hits were coming during Monday morning film sessions -- "The quarterback at Foxborough High could make that throw," Belichick often would say after replaying a Brady misfire -- but he could take it, secure not only in the knowledge of his singular impact on Belichick's career but also in the theater of it all, that the coach was doing it in part to send a message that nobody was above criticism. "Tommy is fine with it," his father, Tom Brady Sr., said years ago over dinner in San Mateo, California. "He's the perfect foil for it."

Brady is less fine with it this year. People close to him believe that it started after last year's playoff win over the Houston Texans, in which Brady completed only 18 of 38 passes and threw two interceptions. Belichick lit into him in front of the entire team in a way nobody had ever seen, ripping Brady for carelessness with the ball. "This will get us beat," he told the team after replaying a Brady interception. "We were lucky to get away with a win."

The criticism has continued this year, as Brady has been hit a lot and battled various injuries. Atypically, he has missed a lot of practices and, in the team's private evaluations, is showing the slippage of a 40-year-old quarterback even as he is contending for MVP and is as deadly as ever with the game on the line. Injuries to his shoulder and Achilles have done more than undermine claims that the TB12 Method can help you play football virtually pain-free. Subtle changes have at times hampered the offense and affected the depth chart. On a fourth-quarter play against the Los Angeles Chargers, for instance, Brady had a clean pocket and a first read open deep, possibly for a touchdown. But Brady got rid of the ball quickly over the middle to receiver Chris Hogan, who had nowhere to run and was hit hard, injuring his shoulder. He missed all but one game of the rest of the season. "Tom was trying to get it out quick," a Patriots staffer says. "As fragility has increased, nervousness has also increased."

At the same time, as his age has increased, Brady has become an advocate of positive thinking. Belichick's negativity and cynicism have gotten old, Brady has told other Patriots players and staff. He feels he has accomplished enough that he shouldn't have to endure so much grief. Patriots staffers have noticed that, this year more than ever, he seems to volley between unwavering confidence and driving insecurity. Brady has noted to staff a few times this year that, no matter how many game-changing throws he makes, Belichick hasn't awarded him Patriot of the Week all year.

Those who know Belichick and Brady well are amazed that they've co-existed this long, two ruthless and proud self-made men, both secure though still unfinished in their legacies, both loved and hated, both having received stiff penalties for cheating, both motivated by ego, humility and -- as much as anything -- doubt. Belichick is famously secretive, creating an entire system in which knowledge flows directly to him and only he decides how to deploy and exploit it. And Brady is famously unhelpful toward his backups -- or, at least, a threat like Garoppolo. The two quarterbacks were friendly, but Brady -- like Joe Montana to Steve Young and Brett Favre to Aaron Rodgers -- didn't see it as his role to advise Garoppolo, even on matters as trivial as footwork, as nobody had helped him during his climb. Garoppolo played well in 2016, starting in place of the suspended Brady, and Belichick began to see Garoppolo as the final piece of his legacy, to walk away in a few years with the Patriots secure at quarterback. But after Garoppolo was knocked out of his second start because of a shoulder injury, he set up a visit at TB12. As he later told Patriots staffers, when he arrived, the door was locked. He knocked; nobody was there. He called TB12 trainers but nobody answered. He couldn't believe it, Garoppolo told the staffers, and that night ended up visiting team trainers instead. Guerrero vehemently denies ever refusing to see any player, and Garoppolo was eventually treated at TB12 -- but it was two weeks after he showed up for his original appointment, and only after a high-ranking Patriots staffer called TB12 to inquire why Garoppolo hadn't been admitted.

Several times this past October, Brady met with Kraft to discuss playing longer. That same month, he also met with Belichick, who was skeptical of a long-term contract extension but was content to start Brady as long as he was the best quarterback. Belichick understood how much Brady had meant to the franchise, and had always insisted privately that he wouldn't move on from Brady unless he could convince the coaching staff of it. But the reality was that no quarterback has ever played at a championship level into his 40s. The meeting ended in a "little blowup," according to a source. Complicating matters was that Garoppolo would be a free agent at the end of this season. Complicating matters more was that Brady and Garoppolo share Yee as an agent.

And complicating matters even more was that Belichick didn't want to trade Garoppolo. He had passed on dealing him last spring, when Garoppolo was in high demand. In early September, Belichick did trade third-string quarterback Jacoby Brissett to the Colts for wide receiver Phillip Dorsett. "If we trade Jimmy, we're the Cleveland Browns, with no succession plan," one person inside the organization said earlier in the year. The Patriots repeatedly offered Garoppolo four-year contract extensions, in the $17 million to $18 million range annually that would go higher if and when he succeeded Brady. Garoppolo and Yee rejected the offers out of hand, for reasons that remain unclear, and the Patriots knew they couldn't make any promises to Garoppolo about the timing of a transition at quarterback without it getting back to Brady.

Two weeks before the Nov. 1 trading deadline, Belichick met with Kraft to discuss the quarterback situation. According to staffers, the meeting ran long, lasting half the day and pushing back Belichick's other meetings. The office was buzzing. The meeting ended with a clear mandate to Belichick: trade Garoppolo because he would not be in the team's long-term plans, and then, once again, find the best quarterback in the draft and develop him. Belichick was furious and demoralized, according to friends. But in the end, he did what he asks of his players and coaches: He did his job. One morning in late October, Belichick texted San Francisco 49ers head coach Kyle Shanahan and asked him to call. Belichick had long admired Kyle's father, Mike, who not only had been one of the NFL's smartest tacticians but had also personally defended Belichick to commissioner Roger Goodell during the Spygate scandal. At the combine this past February, Kyle, weeks into the 49ers job after being the offensive coordinator for the Falcons, met with Belichick for hours to learn from his team's humiliating Super Bowl loss. Belichick believed that Garoppolo would excel under Shanahan, and when he and Shanahan connected on the phone, Belichick offered the quarterback for a second-rounder.

It was a steal, leaving Patriots staffers stunned and confused. Why would the game's shrewdest long-term strategist trade two backup quarterbacks in a two-month span when his starter was 40 years old and banged up? And why did Belichick practically give away a quarterback whom the coaches saw as a potential top-10 player for much less than he could have gotten last spring? It made no sense. Belichick handled the trade as he always does, by not explaining it to the coaches and by burying them so deep in work that they didn't have time to gossip. Most in the organization understood that it was an extreme case, with extreme personalities, but they felt that Belichick had earned the right to make football decisions. Belichick, having always subscribed to the philosophy that it's time to go once an owner gets involved in football decisions, left the impression with some friends that the current dynamic was unsustainable.

Brady, though, seemed liberated. Kraft hugged Brady when he saw him that week, in full view of teammates. A few days later during practice, some players and staffers noticed that Brady seemed especially excited, hollering and cajoling. Brady was once again the team's present and future. His new backup, Brian Hoyer, was a longtime friend and not a threat. The owner was in Brady's corner. "He won," a Patriots staffer says.

In the Patriots' private evaluations, Brady is showing the slippage of a 40-year-old quarterback even as he contends for MVP and is as deadly as ever with the game on the line. AP Photo/Charles Krupa

NOBODY IS BUDGING now. Kraft, Brady and Belichick were supposed to meet in late December to clear the air, but that never happened. It probably won't until after the season. Those interviewed describe a lingering sadness around the team, as if coaches and staff know that the end might be near. Both McDaniels and defensive coordinator Matt Patricia are expected to become head coaches; other assistant coaches might leave to join their staffs or for college jobs, or even retire. The imminent exodus raises the question going forward: Is it possible that Belichick would rather walk away than try to rebuild the staff with a 41-year-old Brady and another year of Guerrero drama -- all while trying to develop a new quarterback? Belichick being Belichick, those around him know nothing of his plans. He has always been a football genius, artfully letting situations play out. The looming uncertainty has taken a toll on everyone, even as the Patriots finished 13-3 and earned the top seed in the AFC playoffs. "Bill's done a phenomenal job of holding the building together," one Patriots official says.

Now 76 years old, Kraft ultimately will attempt to broker a solution. He has paid both Brady and Belichick tens of millions of dollars, won and lost some of the greatest games in NFL history with them, and has stood by both at their lowest moments. He apologized in front of a room of owners for Spygate. And he stood by Brady during Deflategate, even after he backed down and accepted the NFL's penalty. Kraft did so even though many staffers in the building believed there was merit in the allegation, however absurd the case. The team quietly parted ways with both John Jastremski and Jim McNally, the equipment staffers accused of deflating footballs -- they've never spoken publicly -- and Belichick reorganized the equipment staff. Kraft has privately told associates he knew that he went too far in his attacks against the league. "I had to do it for the fans," he has told confidants.

A fifth Super Bowl triumph healed some of those wounds, but there's no guarantee that a sixth will fix the rest. Something has to change, that much everyone knows. Many Patriots players and staff believe that Brady is a good man who has a hard time saying no to Guerrero. They've noticed that he seems to be searching this year, as if reaching the pinnacle of his profession is as fleeting as it is rewarding, manifesting itself in outbursts like the one at McDaniels. Belichick seems to be grinding harder than ever, as if more than a sixth championship is at stake. Before the Patriots played the Steelers in December, he told players, "I brought you here for games like this."

But Belichick also has taken a longer view, as though he sees pieces of his impact leaguewide. He's preparing assistant coaches for job interviews elsewhere, which he didn't always do in years past. He has taken pride in Garoppolo's 5-0 record in San Francisco -- and in the fact that Kraft has confessed to people in the building that trading Garoppolo might have been a mistake. He reset a toxic relationship with the Colts with the Brissett trade. He has even become good friends with Goodell. The two men had a long and private meeting, which two sources told ESPN occurred during the off week after the regular season, when the commissioner visited Foxborough. The NFL says the meeting happened last year, not within the past week.

Belichick always had a vision for how, after more than four decades in the NFL, he wanted to walk away, beyond setting up the team at quarterback. He wanted his sons, Brian and Steve, both Patriots assistants, to be established in their football careers. And he wanted the winning to continue without him, to have a legacy of always having the best interests of the franchise in mind. Both Brady and Belichick have redefined how much influence a coach and quarterback can have on a team game. But this year has shown that the legacy of football's greatest coach, like the game itself, is beyond his control.

A FEW HOURS before the Patriots played the New York Jets in the regular-season finale, Belichick walked straight out of the locker room and out to the field. It was 13 degrees before kickoff with subzero wind chill, the coldest regular-season game in team history, but he was wearing a short-sleeve T-shirt, shorts and receiver gloves. Pictures of him went viral, and for a moment it was reminiscent of a legendary playoff game 16 years earlier, when the Patriots played the Raiders in the snow. That night, Brady once recalled in an NFL Films interview, he took the field for warm-ups wearing a sleeveless T-shirt in the thick snow. He was 24 years old, at the beginning of a career only he saw coming. He wanted to send a message to everyone watching that nobody was tougher, both mentally and physically, than this California kid. That night, Brady showed that he was immune to the stage, a deficit, the weather and a stout defense. It was clear that the Patriots had something special, both at quarterback and under the headset, and it created a moment, both emboldening and addictive, that has lasted far longer than anyone could have expected.

On Sunday, the moment -- their moment -- seemed as alive as ever, to the outside. Belichick ordered the field crew to hang thermometers in the hallway outside of the Jets' locker room, just to mess with a franchise he still hates so much that he barely mentions his years there in the Patriots' media guide. The game unfolded like many have for the Patriots this year, with Brady looking mortal at times and like an MVP at others. As usual, the Patriots won. It didn't look like Belichick's last regular-season game as the Patriots' head coach, but several coaches and staffers later remarked to one another that it felt as if it could be. As Brady and Belichick left the field, bundled up in the cold, the only thing clear was that the beginning of the end started a long time ago, masked by success and the joy and pain of the rise, leaving both men this year's playoffs and their collective will to stave off the fall.