Was the defining moment of the Mets’ ultimately unsatisfying season the three-game, early September sweep at the hands of the lovably losing Cubs, a game bunch of outmanned kids? 

Or maybe it was three even later games in Atlanta, where some Mets people acted jittery about a hurricane that never came, unless you count the defending-champion Braves sweeping them away like a mound of dust? 

Or might it be the season-ending, wild-card series against the Padres, where they barely hit, two of their vaunted three starters were torched and they were dispatched from a postseason derby that looked rather ominous down a long road they never really reached? 

It’s a tough call, one disaster following the next. But suffice it to say, the Mets, as impressive as they played at times over 162 games, were at their worst when it counted most, including in the 6-0 defeat Sunday at Citi Field. 

“It’s a hard pill to swallow,” Pete Alonso said. “They just flat-out beat us.” 

Not that this is any solace, but based on what transpired against the Padres — a very nice team missing its best all-around player, Fernando Tatis Jr. — the Mets were never going to survive the gauntlet that is the National League derby, anyway. If they couldn’t come close to beating a good Padres team, maybe it’s better they never got to Los Angeles, where an all-time great team would have been waiting. 

How would they have done against the likes of Freddie Freeman, Mookie Betts and Trea Turner when Trent Grisham — .184 hitter in the regular season — absolutely crushed them, homering in each of the first two games and reaching base four times in the sorry finale? 

And exactly how were they going to beat the Braves in a long series if they somehow got to the NLCS? The Mets played a nice first five months but appeared to be disintegrating before our eyes. They had one hit in the dreary finale — a single by Alonso — the punctuation mark on their unhappy late-season trend. 

The players were disappointed, even disheartened, to be sure. But reality may have sunk in. By the end, not only was the offense missing but it seemed uncertain how many bullets remained for pitching greats Max Scherzer and Jacob deGrom. 

“We had a great season. We just didn’t get the job done in the postseason,” Francisco Lindor said. 

To a man, Mets players told us how excited they were to play in such a vital game. And yet, their performance showed a decided lack of inspiration. It was really a shockingly poor effort from a team that won the second-most games in its history, and worked hard over a 180-day schedule to improve by 24 games over a year ago. 

The fans came primed to celebrate, but had the natural New York reaction to one of the worst performances of the season. The booing began in the fourth inning, and continued intermittently. 

All the while the Mets were doing nothing — literally — against No. 3 Padres starter Joe Musgrove. Musgrove used a terrific mix of pitches including a devastating curveball to author the most impressive outing by any pitcher in this series filled with pitching greats — seven innings of one-hit ball. 

“Hats off to [Musgrove],” Lindor said. “He flat-out beat us.” 

Musgrove was so befuddling for Mets hitters that Mets manager Buck Showalter suspected him of doctoring the baseball, or at least raised that suspicion in a meeting with umpire Alfonso Marquez before the sixth inning. 

The umps dutifully checked Musgrove after conferring for what seemed like an eternity, and even rubbed his ears. The tactic failed. His ears were clean, and when he resumed pitching he continued his domination over the suddenly inept Mets. 

“We just didn’t have the same magic, the same spark, as we started the season with,” Mark Canha said. 

The Mets did a lot of good things this season. You don’t win 101 games by accident. You don’t dominate over five-plus months without making a lot of great decisions, and doing a ton of things right. They brought in five free agents, and every one of them thrived. Nobody bats 1.000 in free agency. But they did. 

Not sure how much, if any of that, will be recalled anytime soon. Fresh on the minds of Mets fans are the results of the series against the Cubs, Braves and Padres, where the Mets scored only 21 total runs in nine games. The loss of Starling Marte for most of September hurt, but that won’t get it done. The Mets never lost more than three games in a row over a 162-game slate, yet did it twice in crucial late-season series, eventually costing them what seemed like a certain NL East title when the new rules gave it to the Braves via the head-to-head tiebreaker. 

“We didn’t finish as strong as we started,” Canha said, sadly. “That’s what the story is going to be.”