Is Matt Patricia being groomed as Bill Belichick’s heir?

Bill Belichick (left) and his new right-hand man Matt Patricia kept an eye on practice Thursday.Steven Senne/Associated Press

FOXBOROUGH — Matt Patricia’s return to the Patriots after a three-year stint in Detroit is, like most things in Foxborough, shrouded in mystery.

The Patriots website does not list Patricia on the coaching staff. Bill Belichick has been vague about Patricia’s role all offseason, and was again when asked about it Thursday.

“His advice and counsel and presence has been valuable for us in a lot of ways,” Belichick said. “So yeah, I’m extremely glad that he’s here and appreciate the contributions that he gives us on a daily basis.”

Patricia isn’t just contributing to the cause, though, and he’s not back in Foxborough just to be a defensive coach again. While Josh McDaniels, Steve Belichick, and Jerod Mayo are all discussed as potential heirs to Belichick, it is Patricia who looks as though he is being groomed for a major role — either in coaching or the front office.

Belichick lost his two closest confidants this offseason; Nick Caserio became Houston’s general manager, and Ernie Adams retired (though he watched most of Thursday’s practice from the sideline).

Patricia, a 14-year Patriot in his first stint and one of Belichick’s favorite protégés, has returned to lead Belichick’s new brain trust.

At Thursday’s practice, it was Patricia standing shoulder-to-shoulder with Belichick for the first 30 minutes. During the draft, it was Patricia working the phones and serving as Belichick’s sounding board before drafting Mac Jones.

And, most intriguingly, it is Patricia’s signature on the bottom of every free agent contract the Patriots signed this offseason.

That’s right — Patricia, the Patriots’ defensive coordinator from 2012-17, has moved upstairs to the front office. He’s now taking on some of the roles formerly held by Caserio, who was Belichick’s top personnel man for more than a decade.

Patricia was the one who signed Cam Newton’s new contract in March. And since then, every one of the contracts for the 25 players the Patriots signed in the main wave of free agency — Hunter Henry, Jonnu Smith, Matthew Judon, Nelson Agholor, David Andrews, etc. — was signed by Patricia as the Patriots representative.

I reached out to a couple of high-level NFL executives — one retired, one currently with an AFC team — for insight on what that means.

“The fact that he is the one signing all of them, it certainly says that he’s intimately involved, and probably leading the internal organization around cap management and contract negotiations,” the retired executive said.

Is Patricia now the Patriots’ de facto GM? Of course not. Belichick is the boss. He is the one setting the course and making decisions in free agency. One NFL agent said he did not have much contact with Patricia during the negotiation before his player signed with the Patriots.

Patricia is just the closer, which used to be Caserio’s job. Belichick would negotiate the general terms with the main free agents, and Caserio would finish up the details and get the contract filed. Caserio also handled the signings of the bottom-of-the-roster players without much input from Belichick, because those contracts were fairly simple.

With Caserio gone, and Belichick having lost several executives and confidants, Patricia returns as one of the few people he trusts. Patricia began as a Patriots grunt in 2004 (putting aside his degree in aeronautical engineering from RPI), and Belichick was his most vocal supporter before and after Patricia got the job as Lions head coach in 2018.

“Matt’s as hard a working guy as I’ve ever been around. He grinds it,” Belichick said then. “He’s smart, too. He put together those rockets there in college.”

Caserio was famously a jack-of-all-trades for the Patriots, coaching drills in practice while also running the front office. Patricia is now being used in a variety of ways, as well. On Thursday, Patricia taught technique to defensive linemen and observed defensive drills over the second half of practice.

A team source said that Caserio did so much for the Patriots that Belichick had to split Caserio’s responsibilities among several people inside the new inner circle. Dave Ziegler and Eliot Wolf picked up the slack in free agency and also were involved in the contract process, but they haven’t gotten much credit publicly because “only one name goes on the contract.” Matt Groh also gained additional responsibilities in the draft process.

But it is Patricia who has Belichick’s ear in all aspects of the organization, and Patricia who was chosen to be the one in charge of the contracts. “Fair to say Matt did pick up a lot of slack on contracts,” the team source said.

The Patriots have always had someone other than Belichick sign their contracts — Scott Pioli, Floyd Reese, Caserio, and now Patricia. The common thread is that they are from the football side, not the contracts/salary cap/legal side.

This makes the Patriots a bit of an outlier in the NFL, per the AFC executive. Most teams have their contracts signed either by the general manager or lead salary-cap administrator. But Belichick has always preferred having a football person as his contracts guy.

“I can see why they do it; it kind of cuts out the middle man,” the AFC executive said. “They know the comps, they know how the player fits in a scheme. You don’t have to go back and forth between the football side and the salary-cap side when you’re doing a deal.”

At minimum, Belichick is doing Patricia a huge favor by giving him front office experience. Patricia’s three-year tenure as Lions coach ended with a 13-29-1 record, but he would be a much more attractive candidate now that he has experience in contracts and salary-cap management. Patricia may be in Foxborough for at least two seasons, as he is still being paid by the Lions through 2022.

“This is great for Patricia,” the former executive said. “This will position him from a résumé perspective to have as many boxes checked, if not more, than any other coach.”

At maximum, Belichick is grooming Patricia to be the Patriots’ lead front office man for the foreseeable future, and — who knows? — maybe the head coach or GM after Belichick retires.

“There’s no doubt it’s a possibility,” the retired executive said. “It may just be Bill having a lot of faith in him and wanting to stay more focused on other things. But it certainly doesn’t seem like he would just drop it in there for Patricia if he wasn’t already giving him a plan over time to kind of use him in this area.”