If the New York Mets fail to reach the postseason this weekend, media and fans will talk all winter about how this team choked for a second straight September. Chances are, heads will roll and a new on-field staff will man the Mets going into their first season at the new ballpark.

The offseason talk about how the team is populated with choke artists and doesn’t have the personality to win will be non-stop. There are more measurable factors that can be attributed to New York’s slide, however, and one thing is clear: the bullpen hasn’t done its job down the stretch. Teams that can’t finish games can’t finish seasons.

It’s been a rough year for the pen, with or without closer Billy Wagner, whose season ended nearly three weeks ago, when it was decided he would undergo Tommy John surgery on his ailing elbow. If all 2008 games were eight-inning affairs, the Mets would have entered Friday with an eight-game lead over the Phillies in the National League East.

The New York bullpen has a 4.22 ERA on the season. Only four NL pens have higher marks. The bullpen’s 5.02 second-half ERA has hurt the club immensely, and its problems have only worsened in September.

In New York’s last 13 games, the bullpen has posted a 6.63 ERA and allowed opponents to bat a hefty .338. Leads have slipped away and close games have turned lopsided against the Mets.

On Sept. 14, the Mets took a 4-2 lead over Atlanta into the ninth, but relievers Luis Ayala and Pedro Feliciano combined to retire just one batter and cough up five runs in a heartbreaking loss at Shea Stadium.

Prior to that loss, the Mets had a 2.5-game lead over the Phillies in the NL East race. With that loss, though, the Mets kicked off a 5-8 tailspin.

New York went on the road the following day, and the bullpen couldn’t keep the team in a tight game with Washington. The Mets lost to the lowly Nationals, 7-2, and made it three straight defeats by falling to the Nationals again in the second game of the series.

With those three losses, the Mets’ grip on first place in the NL East slipped to a half-game. They lost three straight again a week ago to drop 2.5 games behind the Phillies. In the second of three in a row on Sunday, the pen allowed four eighth-inning runs and blew a late lead in another hard-to-digest defeat to Atlanta.

On Wednesday, with the Mets holding a one-game edge over Milwaukee in the wild-card chase, Cubs slugger Aramis Ramirez stroked a 10th-inning, two-run homer off Ayala, who gave up the final three runs in a 9-6 loss. Milwaukee beat Pittsburgh that night and pulled into a tie with New York.

The Mets might have been rejuvenated when they pulled the late-comeback trick on the Cubs in the series finale Thursday. They trailed 6-3, but scored once in the seventh inning, twice in the eighth to tie the game, and won it in the last of the ninth on an RBI single by Carlos Beltran.

Any momentum, or whatever intangible that might be sparked by an all-important comeback victory, didn’t reach the Mets. On Friday night, they scored a single run and dropped the opener of their season-ending series with Florida, 6-1. With both the Phillies and Brewers pulling out wins Friday, the Mets fell two games back of the East-leading Phils and a game behind the Brewers in the wild-card standings.

It’s déjà vu all over again, as it was the Marlins who knocked the Mets out of the NL East race in 2007. Playing at home, New York lost two of three games to Florida in its final series of the season, including a defeat in the finale that gave Philadelphia the NL East title.

With so much on the line, the Mets will call on Johan Santana to pitch Saturday’s matchup on three days’ rest. The southpaw is 7-0 with a 2.00 ERA in his last 13 starts, and he’s 4-0 (2.49) lifetime against the Marlins.

On the other hand, Santana’s worked on three days’ rest only once as a major leaguer, when he faced the Yankees twice in the 2004 playoffs. This time, Santana goes on short rest after throwing a career-high 125 pitches in a 6-2 victory over the Cubs Tuesday. In the 2004 Division Series, he went just five innings after just three days off, following a 93-pitch effort in the first of his two starts.

That means Saturday’s game may come down to the bullpen. The same is true Sunday, when Oliver Perez is scheduled to pitch on three days’ rest. So, it’s the pen that may keep the Mets on the sidelines when October baseball begins. Or it could be critical to a miracle finish this weekend.

The Mets will need some help from the Nationals and Cubs, the teams playing the Phillies and Brewers, but the importance of the bullpen can’t be overstated. It's undoubtedly a key to the Mets’ chances of claiming a postseason berth in the next 48 hours.