The fate of the 2020 Mets revolves heavily now around rebounds and rehabs. Perhaps no team has a wider variance of who they could be next season.

Jed Lowrie has become a punch line and still might be traded, but he was an All-Star in 2018 before hardly playing last year. Yoenis Cespedes — cue the punch line again — is predicting at least 40 homers next season, and would you absolutely bet against 30 if he is able to play regularly, considering his talent and motivation to recoup lost dollars?

There is a Cy Young in Rick Porcello’s recent past and excellence in Michael Wacha’s.

But the Mets probably would have made the playoffs last year if their pen were strong even with little from Lowrie, nothing from Cespedes, and Porcello and Wacha on other teams. And the distance from condemned to contending for the 2020 Mets again is going to be dictated by a pen that only grew greater in divergent possibilities with the Christmas Eve signing of Dellin Betances.

In 2018, Edwin Diaz, Jeurys Familia and Betances were three of the top 19 relievers by Wins Above Replacement (FanGraphs), combining for 209 games, 212 innings, a .188 batting average against, a 37.7 strikeout percentage, a 2.59 ERA and 7.0 WAR. In 2019, their aggregate was 133 games, 118 ²/₃ innings, a .261 batting average against, a 30.9 strikeout percentage, a 5.61 ERA and -0.1 WAR.

Where do the Mets sign up for even 80 percent of 2018? Because if they get that, then why not them? Why couldn’t they emerge from the competitive NL East logjam with the Braves, Nationals and Phillies? There is the potential for a bullpen as good as that of the Yankees. And there is a chance for a dumpster fire of inadequacy and injury that would leave the Mets undone once more by relief. The swing could be that great.

For the Mets, adding Betances to the risk is worth the potential reward. As opposed to Diaz, he has shown he can handle New York, now completing his five borough odyssey: raised in Manhattan, school in Brooklyn, minors in Staten Island, Yankees in The Bronx and Mets in Queens.

With their obsession for and pitching-record contract to Gerrit Cole and their unwillingness or inability to yet trade J.A. Happ, the Yankees have reached what they have set as a max payroll to begin 2020. Thus, even if they were comfortable with Betances’ physical issues, the $10.5 million the righty is guaranteed at minimum was beyond Hal Steinbrenner’s restrictions.

There are major physical concerns. An injured shoulder limited Betances to two September batters in 2019. He struck both out, did a small celebratory leap and partially tore his left Achilles tendon. That is the landing leg for the 6-foot-8 pitcher. His Achilles, more than his shoulder, scared teams. Not only because of the injury, but because Betances’ delivery could get out of whack even before perhaps compensating for the injury, plus his fielding and throwing to bases were poor prior to questions about how he would bounce off the mound now.

The Mets’ early read is that Betances will be a go for spring training and they feel they have insights into his health. Their team doctor, David Altchek, who works out of the HSS Sports Medicine Institute, gave the second opinion on Betances’ shoulder during the season. Dr. Martin O’Malley, also of HSS, who did the Achilles surgery on the Nets’ Kevin Durant, has been in charge of Betances’ Achilles rehab. That both are New York-located appealed to Betances, as did having his good friend from their Yankees days, Carlos Beltran, as manager.

The Mets wanted Betances because they would rather take an upside play — when right from 2014-18 Betances was among the majors’ five best relievers. With the way his contract is structured, with relatively low bases for a 2021 player option and 2022 vesting player option, it was worth the Mets’ financial gamble. There is an optimistic scenario in which Betances, Diaz and Familia veer toward 2018, while Seth Lugo and Justin Wilson trend toward 2019, leaving the Mets a powerful five-man pen with Brad Brach, Robert Gsellman and Steven Matz (assuming Porcello and Wacha are both in the rotation) for depth. That is a long way from needing Jacob Rhame or Drew Gagnon for vital outs.

But we also are a long way from knowing who Betances — or Diaz or Familia — will be. One door, NL East prominence. The other door, a repeat of 2019.