It’s down to this.

After six weeks of spring training and a six-month season, the Phillies must win at least one game in Atlanta this week to stay alive and probably must sweep the three-game series to have a real chance of overtaking the Braves for the National League East title. Otherwise, the longest active playoff drought in the NL will extend to a 10th consecutive season.

“You get to the end of the year and you look to have an opportunity to get to the playoffs,” said manager Joe Girardi, whose Phillies open a three-game series with the Braves on Tuesday. “That’s exactly what we have. We have an opportunity to get there. It’s exciting. We have a shot.”

Baseball Prospectus sets the Phillies’ playoff odds at 15.3%. Fangraphs puts it at 13%. Baseball-Reference: 10%. So, yeah, it doesn’t look great. But if we’ve learned anything in the last few weeks, it’s that fortunes can change quickly.

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Inquirer baseball writers Scott Lauber and Matt Breen are here to preview the Phillies’ biggest regular-season series in at least a decade.

Do the Phillies have to sweep the Braves?

Scott Lauber: Mathematically, no. Realistically, yes. The margin for error here is slim. How slim? Any combination of five Braves wins and Phillies losses will clinch Atlanta’s fourth consecutive division title. So the Phillies could win two of three and still have a chip and a chair, as old friend Gabe Kapler would say, when they get to Miami on Friday. It just wouldn’t be a very sturdy chair.

In 2007, the Phillies were 2½ games out of first place going into the last week of the season. They finished only 4-2 but won the division by one game over the New York Mets, who went 1-6. Sweeping the Braves would be the best way to author a similar comeback.

Matt Breen: Yes. I said last week the Phillies had to win six of their seven games on the last homestand. Instead, they won five and now head to Atlanta trailing by 2½ instead of 1½. That one game seems like a big difference. If the Phillies sweep Atlanta, then they control their own fate. If they win two, then they’ll be asking the Mets, who open a series in Atlanta on Friday, for help. Good luck with that.

What’s the key to winning the series?

SL: The Phillies have to hit, plain and simple. And we’re looking at you, J.T. Realmuto. And Andrew McCutchen. And Didi Gregorius.

Realmuto was 10-for-26 with seven RBIs on the homestand last week, but then left four men on base in Sunday’s 6-0 loss to the Pittsburgh Pirates. Gregorius finally delivered a few big hits last week, too. But the Braves will throw their three best starters — Charlie Morton, Max Fried, and Ian Anderson — so the Phillies’ offense needs to be more than just Bryce Harper.

MB: It’s safe to count on Zack Wheeler on Tuesday night in the biggest start of his career, but how about Aaron Nola on Wednesday? He gave up six runs last week against the Pirates. Yes, some contact was soft, but six runs are six runs. His September has been rather forgettable and his season has been inconsistent. But he can change that narrative by pitching a gem in what is also the biggest start of his career. The Phillies will need their starting pitching this week, but Nola is the key.

What would making the playoffs mean for the franchise?

SL: Let’s invoke 2007 again. The Phillies hadn’t made the playoffs since 1993, and although there was a legitimate reason to be optimistic about a homegrown core led by Jimmy Rollins, Chase Utley, Ryan Howard, and Cole Hamels, there was also healthy skepticism that they would get over the hump after postseason flirtations in 2003, 2004, and 2005. Never mind, then, that they got smoked in the division series by the Colorado Rockies. It did wonders for the psyche of the organization and the fans just to get there.

The same thing is true now. The Phillies have too many flaws — and way too little pitching — to forge a deep playoff run. But slingshotting past the Braves and getting into the playoffs would help Harper, Realmuto, Nola, and others exorcise the demons of the last two Septembers. And that would be no small thing.

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MB: It would mean a lot. The Phillies didn’t sign Harper for $330 million to finish in second or third place every year. He was supposed to be their ticket not only to the postseason but to postseasons. So far, it hasn’t happened. Now he’s having one of the best seasons of his career yet they’re still on the outside looking in.

The Phillies have to get Harper into October and they also have to give their fans postseason baseball again. It’s been 10 years, which is hard to believe as the Phillies were the class of the National League for nearly five seasons before it all came tumbling down. It’s been a long road back to relevance, but no one expected it to take this long to simply reach the playoffs again.

What would missing the playoffs mean for the franchise?

SL: Before the season, most of us pegged the Phillies to win 82-85 games. In that sense, they will meet expectations. But competing for a division title until the last week of the season only to fall short is akin to Lucy repeatedly pulling away the football from Charlie Brown just as he’s ready to kick it. After a while, it becomes self-defeating.

Regardless of how this week goes, the Phillies must reckon with a hole-filled roster and a player-development system that hasn’t developed many major-league players in the last 10 years under multiple general managers. Dave Dombrowski has a long, complicated offseason to-do list. But winning the NL East, even in a blah year, would make everything seem a little less daunting.

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MB: It would be the start to an offseason that I expect should be busy for Dombrowski. He was brought here to mold the Phillies into a contender, but it was obvious that this wouldn’t be a quick fix. Dombrowski was hired in the middle of last offseason during the pandemic, so he didn’t get a true shot to put his fingerprints on the team. He’s now had more than nine months to evaluate the organization and some changes are already underway.

This winter, he’ll have plenty of areas — left field, center field, shortstop, third base, bullpen, rotation — to address. And it will be interesting to see what he does. Yes, we pegged the Phillies to be .500 in 2021, but they need to do enough this winter to have playoff expectations in 2022. It’s been long enough.