PORT ST. LUCIE — Moving from super agent to Mets GM last year presented a whole new world to Brodie Van Wagenen, a world he had to live and learn.

Van Wagenen was at the minor league complex Wednesday along with the entire major league coaching staff and the staffs of the Double-A and Triple-A teams and other personnel, coordinators and such, to get a head start on the 2020 season.

Coming together and discussing ideas and putting those ideas into practice is a key ingredient if the Mets are to attain success after a strong winter of preparation.

“One of the many learning lessons I had from 2019 is the small marginal difference between winning and losing,’’ Van Wagenen told The Post. “Good teams capitalize on the small things and teams that lose games miss out on execution of the small things.

“In the first half of the year we lost so many games by small margins and reflecting on how correcting those little details can entirely spin the season. With that in mind that’s why the focus has been on the offseason preparation.

“Our focus is on the little things, the minutiae, because we have talent. It’s the matter of being able to combine the focus every day to win games.’’

Cutting down those mistakes and developing players and making the most of your talent is what it is all about. That is a big difference in approach from last season, when Van Wagenen offered this challenge to the NL East: “Our goal is to win a championship and it starts with the division, so come get us.’’

That bravado has been replaced by preparation as Van Wagenen and his top assistants, Allard Baird and Adam Guttridge, get ready for the season as Luis Rojas takes over as manager.

“No question I learned a lot,’’ Van Wagenen said. “There was so much new. I’m a believer we all have to grow every day and recognizing each day offers something new.

“We have high expectations. We have to continue to raise the expectations for ourselves and that includes the general manager, the player development guys, the health and performance department. We have to continue to set high expectations and be willing to do the work it takes to achieve them.’’

The Mets had a first half to forget but finished strong as they missed out on a wild-card berth.

“One of the learning lessons from last year was the importance of identifying problems before they happen is so key,’’ Van Wagenen said. “See them, communicate them and problem-solve before they escalate into problems.’’