Ahead of the start of training camp, The Post’s AFC East primer:

New England Patriots 

Coach: Bill Belichick (24th year) 

Training camp site: Foxborough, Mass. 

Key additions: After throwing for just 208 yards per game last season, the Patriots remodeled their weaponry around TE Mike Gesicki and WR JuJu Smith-Schuster.

OTs Riley Reiff and Calvin Anderson could battle for one starting job.

Defense was a two-day focus of the draft, including rookie CB Christian Gonzalez — one of the first-round steals. 

Key losses: Raiders head coach Josh McDaniels raided his former team for WR Jakobi Meyers and trusted backup QB Brian Hoyer.

Two disappointments — former first-round pick OT Isaiah Wynn and former free-agent splash TE Jonnu Smith — got needed changes of scenery.

Nelson Agholor was on the outgoing end of the receiver carousel.

S Devin McCourty retired after a terrific 13-year career. 

The Patriots’ quarterback position is Mac Jones’ to lose.

Training camp storylines to watch: Quarterback is Mac Jones’ job to lose.

Offensive coordinator Bill O’Brien returns as a white knight to turn around last year’s dysfunction.

O’Brien has a relationship with Jones through their non-overlapping Alabama ties.

There are battles at kicker and punter, after two draft picks were spent on specialists.

The McCourty-less defense returns its other 10 starters to a unit that reached 30 takeaways and 50 sacks last season.

If free agent WR DeAndre Hopkins lands here, it’s a game-changer. 

Buffalo Bills 

Coach: Sean McDermott (seventh year) 

Training camp site: Rochester 

Key additions: OLB Leonard Floyd (29 sacks in the past three seasons) followed his former Super Bowl-winning Rams teammate Von Miller across the country. OG Connor McGovern is a projected starter.

RBs Damien Harris and Latavius Murray will try to take some of the rushing load off of QB Josh Allen.

Rookie TE Dalton Kincaid could be prolific in the slot. 

Key losses: LB Tremaine Edmunds received one of the biggest free-agent contracts of the offseason to join the Bears.

RB Devin Singletary — never a focus of the offense despite 56 career starts — bolted for the Texans. WR Isaiah McKenzie (Colts) and S Jaquan Johnson (Raiders) made big plays in bit roles over the years. 

Training camp storylines to watch: S Damar Hamlin is back practicing after his near-death on-field experience last season.

Everything else is less significant, but … is WR Stefon Diggs a powder keg waiting to explode?

Diggs’ sideline outburst aimed at Allen in a playoff loss fueled offseason trade speculation, which led to skipping the first day of mandatory minicamp.

Stefon Diggs
Stefon Diggs has been the source of ample offseason speculation.
Getty Images

All is supposedly resolved.

McDermott is taking on defensive play-caller duties for the first time as a head coach after ace coordinator Leslie Frazier’s surprise leave of absence. 

New York Jets 

Coach: Robert Saleh (third year) 

Training camp site: Florham Park, N.J. 

Key additions: Call them “Packers East.”

Landing QB Aaron Rodgers is the biggest move for the franchise since drafting Joe Namath.

WRs Allen Lazard and Randall Cobb, and OT Billy Turner are reunited with Rodgers and offensive coordinator Nathaniel Hackett.

Speedy WR Mecole Hardman slides into Braxton Berrios’ return role.

S Adrian Amos was signed as soon as Chuck Clark suffered a season-ending injury. 

Key losses: The defensive line was weakened by losing Sheldon Rankins and Nathan Shepherd.

Expecting Seahawks exports Quinton Jefferson and Al Woods to pick up the slack is a big ask. Fan-favorite QB Mike White is no longer insurance off the bench.

WR Elijah Moore was traded to the Browns after a roller-coaster two seasons. 

Training camp storylines to watch: Start with the new offense’s chemistry, Rodgers’ health (fractured thumb last season) and his motivation to cement his legacy in a new place.

Even with Quinnen Williams’ contract dispute resolved by a new extension, there’s so much more: In the left tackle battle between Mekhi Becton and Duane Brown, does the loser play right tackle or is that Turner’s job?

Quinnen Williams reacts after making a play for the Jets.
Quinnen Williams has even more to celebrate after securing a $96 million contract from the Jets.

Will RB Breece Hall be back from a torn ACL before Week 1?

All of it will unfold during an unwanted appearance on HBO’s “Hard Knocks.” 

Miami Dolphins 

Coach: Mike McDaniel (second year) 

Training camp site: Miami Gardens, Fla. 

Key additions: One year after trading for WR Tyreek Hill, the Dolphins made another splash by dealing for three-time First-Team All-Pro CB Jalen Ramsey.

Five ex-Jets — including White, Berrios and WR Chosen Anderson — crossed rivalry lines.

Jalen Ramsey
The Dolphins traded for Jalen Ramsey this offseason.

Signing LB David Long Jr. was a steal when looking at comparable free agents. 

Key losses: Injury-plagued CB Byron Jones was cut for salary-cap savings.

Gesicki was de-emphasized last season but had been productive.

Three-year starter LB Elandon Roberts joined the Steelers.

QB Teddy Bridgewater’s stay lasted just one year, as is his norm. 

Training camp storylines to watch: How long can QB Tua Tagovailoa stay healthy after his history of concussions marred an MVP-caliber start to the season and led to consideration of retirement?

The Dolphins and Jets are the co-favorites to land free-agent RB Dalvin Cook, but Miami needs him more.

At least four players are thought to be seeking new contracts.

Defensive guru Vic Fangio was hired after a year off to turn around the No. 24-ranked scoring defense by toning down blitzing and taking away big plays allowed.