In the years after, Belichick allowed many of Brady’s teammates to participate in training regimens not with the Patriots’ highly regarded medical and training staff, but at the TB12 Center just outside of the stadium in Patriot Place. Guerrero treated the players there with his alternative methods, and the TB12 Center billed the Patriots for his services.

In 2013, as Tom Brady and Alex Guerrero prepared to launch their TB12 therapy center, Bill Belichick made clear during a sports medicine symposium that he trusted the medical and training staff the Patriots already had in place. He credited the team’s staff with helping to win the franchise’s first three Super Bowls.


Belichick also permitted Guerrero, Brady’s close friend and business partner, to secure his own office near the Patriots locker room, fly on the team charter to road games, and receive credentials to work the sidelines of every game, home and away.

But this season the Patriots coach has reversed course. For reasons he has declined to explain, Belichick weeks ago stripped Guerrero of his special team privileges, restoring a measure of tradition to the team’s medical and training operation, according to several people familiar with the Patriots’ internal operations.

Guerrero is now banned from boarding Patriots jets. His sideline access has been revoked. And he no longer is permitted to treat players other than Brady in his exclusive office at Gillette Stadium.

The development has created some friction in Foxborough, where Belichick and Brady have collaborated over 18 years to help create the first great football dynasty of the 21st century, sources said. But the coach and quarterback, in keeping with their tradition, have refused to publicly address a potentially distracting topic, in this case Guerrero’s diminished status.


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When Brady was asked Monday during his regular weekly appearance on WEEI about a possible rift between Belichick and Guerrero, he said, “I don’t have any comment on that other than to say Alex, it’s been well-documented, has been a huge part of what I do and I’m so fortunate to have him not only as a friend, but with everything that we’ve been able to do together.”

He added, “Alex has been a huge, huge reason why I’m still playing” at age 40. Guerrero is 52.

Tom Brady celebrated with Alex Guerrero after defeating the New York Jets at MetLife Stadium in November 2016. Getty Images/File

Belichick declined to address the issue Monday in his regular interview on WEEI, and Guerrero did not respond to a request to comment for this story.

The Globe reported in 2015 that the Patriots medical and training staff had lodged complaints with Belichick about Guerrero’s expanding role with the team. Their concerns involved Guerrero’s alternative treatment practices often clashing with their own methods as well as his questionable background.

Before Brady made him his business partner, Guerrero had been sanctioned by federal regulators for falsely presenting himself as a medical doctor and deceptively promoting nutritional supplements, according to government records.

Massachusetts state regulators also stepped in when Guerrero began doing business with Brady at the TB12 Center. While Guerrero treated Patriots players and other TB12 clients there, investigators looked into allegations that he was practicing physical therapy without a license. He was cleared of wrongdoing in a 2014 letter instructing him to abide by state regulations while supervising licensed therapists at the TB12 center.


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Belichick indicated to the team’s medical and training staff at the time that his hands were tied because of Brady’s special status with the franchise, according to a source with direct knowledge of Belichick’s exchange with the staffers. The source said Belichick told those who complained about Guerrero: Tom wants him. What am I supposed to do?

By this season, however, TB12’s client list has grown to include most of the Patriots roster – a unique arrangement in the National Football League. With Guerrero effectively involved in the health and training practices of much of the team, it’s not unusual for him and the Patriots medical and training staff to differ, according to sources.

Belichick famously dislikes distractions. He dislikes divisiveness, real or perceived, even more. Internal observers believe that restricting Guerrero’s operations in the stadium might reduce some tension in the workplace, where promoting player health and game readiness is considered a priority.

Alex Guerrero stood near Bill Belichick on the sidelines as the Patriots played the Texans in 2015. Jim Davis/Globe Staff

Under the revised policy, many of Brady’s teammates who have been treated by Guerrero at Gillette are continuing to see him at the nearby TB12 Center. They can be shuttled there in a couple minutes or walk there in less than 10 minutes.

Guerrero, the godfather of Brady’s son Ben, has been a guiding force in the quarterback’s effort to build TB12 into a national brand. He has collaborated on Brady’s best-selling book, “The TB12 Method,” his sold-out, $200 “TB12 Nutrition Manual,” his line of TB12 snacks, protein, and “performance meals,” his TB12 workout gear and apparel, and the bustling TB12 sports center, where there is a waiting list for new clients, according to the company’s website.


Guerrero’s connection to the Patriots began when he started working with former linebacker Willie McGinest in their native Southern California and in Foxborough more than 17 years ago. McGinest recommended him to teammates, and the list of Patriots who have credited Guerrero with helping them extends from Lawyer Milloy to Ty Law, Troy Brown, Wes Welker, Aaron Hernandez, Julian Edelman, and Danny Amendola.

None have entrusted their bodies and invested their futures as deeply in Guerrero as Brady. They drew especially close in 2008 after Brady suffered a career-threatening injury that required reconstructive knee surgery. Guerrero stayed by him throughout the process, closely participating in his care.

“He was pretty much ever-present before, during, and after the surgery,” Dr. Neal ElAttrache, a Los Angeles orthopedist who performed the operation, told the Globe in 2015.

ElAttrache said his mainstream medical practices ran counter to some of Guerrero’s alternative methods.

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Guerrero, having earned a degree in traditional Chinese medicine from the now-defunct Samra University of Oriental Medicine in Los Angeles, follows a holistic approach that involves alternative therapeutic substances and nutrition plans, as he detailed in his 2005 book, “In Balance for Life: Understanding & Maximizing Your Body’s pH Factor.”


However, ElAttrache said he was impressed with Guerrero’s care for Brady and other NFL players upon whom he has operated.

Brady’s bond with Guerrero became so strong that in 2010 he endorsed a beverage called Neurosafe that Guerrero’s supplement company marketed as “a drink that protects your brain from the consequences of sports-related traumatic brain injury.” The company claimed the beverage’s results were scientifically proven.

The Federal Trade Commission asserted Guerrero’s claims were bogus. At that point, Guerrero stopped marketing the product and provided refunds to anyone who bought the drink.

Brady said on WEEI in 2015 that Guerrero has acknowledged making mistakes and has expressed regret for them.

“That’s part of growing up and understanding there are certain things that happen in life that you wish you didn’t do,” Brady said.

Yet some of Guerrero’s training practices have remained at odds with traditional practitioners. When The New York Times Magazine asked him in 2015 if the philosophies of conventional team trainers ever clash with his methods, Guerrero said, “Most of the time.”

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“Everyone thinks I’m a kook and charlatan,” he said.

Patriots chairman and CEO Robert Kraft told the Times that Guerrero’s role with the team “doesn’t come without its challenges.”

“But we have a coach that’s accepting, and we have a leader of the franchise who’s driving it,” Kraft said.

Kraft was not available to comment for this article, though his son, team president Jonathan Kraft, said on his regular radio appearance on WBZ-FM before Sunday’s game that he was unaware of the coaching staff or Guerrero “being upset with each other.”

To Brady, Guerrero’s excellence was embodied by the quarterback waking up Monday after a bruising game against the Steelers in Week 15 of the NFL season and feeling “zero pain,” as he said in his radio appearance.

Rob Gronkowski, too, may be a testament to Guerrero’s philosophy, which stresses maintaining pliability over density in muscular development. He began working with Guerrero after undergoing back surgery last winter.

Gronkowski’s greatest challenge has been durability. Now in his eighth year with the Patriots, he has not played a full schedule since his first two seasons. Yet he appeared as healthy as ever Sunday – after missing Week 14 because of a disciplinary suspension – as he helped to lead the Patriots to a stunning victory over the Steelers.

The last time the Patriots won a Super Bowl, Guerrero was on the field afterward to embrace Brady. This year, he may need to wait for a hug.

Tom Brady with Alex Guerrero after the Patriots beat the Seattle Seahawks in Super Bowl XLIX in 2015. Kathy Willens/AP/Associated Press

Bob Hohler can be reached at robert.hohler@globe.com.