BOSTON -- The moment last season ended, with the Dodgers celebrating their six-game World Series victory at Globe Life Field as the Rays watched from the dugout, Tampa Bay set its sights on nothing short of a championship this year. The six months of the regular season -- all the injuries the Rays overcame, the franchise-record 100 wins they piled up, the 162-game display of the organization’s talent, depth and resilience -- were supposed to just be a prologue. The Rays’ story would be told in October and, maybe, November.

But now their season is over, their run through October cut short after a heartbreaking 6-5 loss to the Red Sox in Game 4 of the American League Division Series on Monday night at Fenway Park. Rather than being the last team standing, they were the first one knocked out of the Division Series round.

• Box score

The Red Sox advanced to the AL Championship Series, and the Rays headed home to reconcile how their remarkable regular season gave way to an early exit in the postseason.

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“These guys should be very proud -- I know I am -- of what was accomplished. You're allowed to be proud and also disappointed at the same time,” Rays manager Kevin Cash said. “Coming into Spring Training, there's no denying this team had high aspirations. … But I can't look at this team as a disappointment. I would say that's unfair.”

This is not the end for Tampa Bay. The club has a young and mostly club-controlled roster featuring a budding superstar in 20-year-old Wander Franco, a deep farm system bursting with prospects and a front office with a keen eye for talent. The Rays set out to build a sustainable contender, and they have done so by reaching the playoffs three years in a row.

Yet they’ve fallen short of their ultimate goal each time, with this defeat perhaps the most surprising one yet.

“It was quick. I think that’s one of the main things when we sat down, like, ‘Wow, I didn’t think it was gonna be over this quickly,’” said reliever J.P. Feyereisen, who allowed the winning run on a sacrifice fly by Kiké Hernández. “We felt good. We played some good games. You come in here, especially with this atmosphere with these crowds and two walk-off wins, that’s tough.”

The mood in the Rays’ clubhouse afterward, they said, was a mix of emotions. Feyereisen said players sat down and talked about what’s next, like a group of friends conversing around a campfire. Reliever Andrew Kittredge acknowledged players were upset. It was “somber,” Cash said.

But Kevin Kiermaier said he was “not disappointed at all” in the immediate aftermath, as every handshake and hug reminded him what a special season it had been.

“With how good they were through the whole course of the regular season, I truly believed we were going to win the World Series,” Kiermaier said. “I really did, with our pitching and our bullpen, just with how many runs we can score offensively. We had all the right pieces to do it, but we just got beat by a really good team over there.”

The Rays had the AL’s best record and claimed their second consecutive AL East title, proving their success last year was more than just the product of a 60-game season. They had every reason to believe they had another deep postseason run in store, too.

After an all-around dominant performance in their 5-0 Game 1 victory, the Rays saw just about everything that could go wrong do exactly that. Reliable relievers Collin McHugh and Matt Wisler faltered in the middle innings of Game 2, the turning point of the series, then Michael Wacha let the game get out of hand in a 14-6 loss. Kiermaier’s 13th-inning ground-rule double, which bounced off Hunter Renfroe and into the bullpen in right-center field to hold the go-ahead run at third, swung the final inning of their 6-4 loss in Game 3.

And after Cash’s decision to bring in starter Shane McClanahan in the third inning of Game 4 backfired in a big way, third baseman Yandy Díaz and first baseman Ji-Man Choi misplayed a Travis Shaw grounder into a pivotal infield single in the ninth, setting up a the game-winning sacrifice fly by Hernández.

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“It’s baseball. It's who's hot at the right time,” catcher Mike Zunino said. “It's a very good team over there. Boston's played us extremely well all year. There's games that we've edged them out in certain circumstances, and they happened to get the edge on the couple games that matter the most. It's tough.”

And just like that, it’s over.

“It's frustrating to have it end here in the Division Series. I think we are a better team than maybe we showed lately,” Kittredge said. “But you know, the Red Sox are a really good team, too, and they played a really good series.”

The resiliency that defined the Rays’ regular season reappeared after they fell in a five-run hole. Their bullpen held the line until the ninth. Jordan Luplow doubled and scored in the fifth. Franco hit a two-run homer in the sixth, capping a spectacular postseason debut. Kiermaier doubled in a run and scored the tying run on Randy Arozarena’s single in the eighth. Kiermaier ended the eighth with an incredible 90 mph throw to Díaz, who tagged out Alex Verdugo at third.

• Kiermaier nails Verdugo late in Game 4

“A pretty telling example of what this team’s character is about,” Cash said.

That spirit led to 46 come-from-behind wins, and the Rays believed they had at least one more in them Monday night. Instead, for the third straight year, the Rays’ season ended with them watching from the dugout as their opponent celebrated in front of them.

“We would have loved to get to the next step and get back to a World Series and try to take that next step,” Kiermaier said. “It just wasn't our time. But the winning way, it's going to continue here. There's just too much talent in our organization.”