PHILADELPHIA — The Mets have agreed in principle to a deal with third-round draft pick Matthew Allan, a source said, but the contract is not final and is pending a physical, which is no small detail.

Locking down Allan, a high school righthander committed to the University of Florida, is the linchpin of Brodie Van Wagenen’s first draft as general manager. Allan was widely considered a first-round talent but dropped because of signability concerns. The Mets said from the start that they were confident they would be able to bring him into the organization, and it appears they are close to fulfilling that goal.

The Mets have about $2.5 million left in their draft bonus pool to sign Allan, significantly more than the approximately $668,000 recommended signing bonus for Allan’s pick, 89th overall.

The Mets have signed 25 of their 40 draft choices, including everybody from the first 10 rounds except Allan. The deadline to sign draftees is July 12.

Familia says no on surgery

On the injured list because of a Bennett lesion — a bony spur — in his right shoulder for the second time this season, Jeurys Familia said Wednesday he has no plans for surgery to fix the long-standing issue.

“I think I just need to go into the offseason and work hard and try to strengthen the muscles around there so I can be OK,” he said through an interpreter.

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While sidelined, Familia and the Mets have identified a small delivery fix that they think can help turn around his season. He has a 7.81 ERA — more than double his career 3.10 ERA — and 1.84 WHIP.

“It’s just getting a little bit longer in my stride in my delivery,” Familia said. “This year I’ve been a little bit shorter. I was watching videos [from last year] and a little bit of different statistics, and I was a little longer. It makes a big difference."

Extra bases

Noah Syndergaard (strained right hamstring) is scheduled to return from the injured list Sunday night to start against the Braves, Mickey Callaway said … Callaway said he will continue to rest Jeff McNeil periodically because “he gets dinged up.” But that doesn’t mean Callaway likes doing so. “When I sit him, I hate it,” Callaway said. “I want him playing every day.”