Only 30 MLB managing jobs exist, making each of them precious, but a Hall of Fame manager sees plenty of reasons the Mets opening is attractive.

“The Mets have been struggling, but you look at what they have and they don’t have and I have to start with the fan base,” Tony La Russa told The Post on Tuesday. “They have a very loyal and passionate fan base, just like that year they went to the World Series [2015] with Terry Collins.

“You look at the other things they have, they have done a great job of developing pitchers and now you have got core young hitters, so I think it’s a combination of the history, the support, and the winning hasn’t been consistent there lately, but that is a great opportunity. You have some assets there. I think a lot of people would like to manage that club.”

The Mets have started contacting candidates, according to an industry source, but it’s unclear whether the first wave of interviews will occur face-to-face with GM Brodie Van Wagenen and his staff or through phone conversations.

Joe Girardi, Buck Showalter and Dusty Baker are marquee names available (with Joe Maddon expected to land with the Angels), but the Mets could also go the first-timer route, with Carlos Beltran, Luis Rojas, Joe Espada or Joe McEwing, among others. Bob Geren, Mike Matheny and Clint Hurdle are experienced names available, albeit without the star-studded appeal.

There is much skepticism within the industry that Beltran would return to the Mets because of his tumultuous relationship with owners Fred and Jeff Wilpon during Beltran’s tenure playing for the team, but the former All-Star outfielder recently attempted to minimize the past.

“You can’t rule anything out in life,” Beltran told MLB.com. “You can’t live life thinking about the past. You have to live in the present.”

Does that mean he would talk to the Mets about the job, if given the opportunity?

“You’d have to listen,” Beltran said.

A key member of Van Wagenen’s staff involved in the search includes Allard Baird, who spent a decade-plus working in Boston’s front office before departing last offseason to become an assistant GM with the Mets. That connection could put at least two Red Sox coaches in play for the Mets managerial opening: Carlos Febles and Ron Roenicke.

Febles, the Red Sox third base coach, played for the Royals during Baird’s tenure as Royals GM in the 1990s and 2000s. And Baird was instrumental in bringing Febles into the Red Sox organization in 2007. Febles served as a minor league manager in Boston’s system for six seasons before becoming a major league coach.

Roenicke was Alex Cora’s bench coach for last season’s World Series winning team. Roenicke also managed the Brewers to the NLCS in 2011.

“I have really been impressed with [Febles’] knowledge, he does infield work and he’s shown really good judgement coaching third — Fenway Park is one of the toughest places around,” said La Russa, who has spent the last two seasons as a Red Sox special assistant. “But more importantly he’s got a way of connecting with players. He’s very good on relationships, which is one of the keys nowadays. You have got to get to know players and connect with them.”

La Russa has needed no introduction to Roenicke, whom he managed against in the NL Central. Roenicke was previously a top lieutenant for Mike Scioscia with the Angels.

“Ron is one of the best baseball men in the game today,” La Russa said. “You look at his résumé and now I have watched him firsthand for a couple of years. There is no man with experience out there that’s better than Ron. He’s right at the top of the list.”