The first round of MLB’s playoffs wrapped up Thursday night when Pete Alonso’s dramatic three-run homer in the top of the ninth helped give the New York Mets a 4-2 win over the Milwaukee Brewers and delivered Alonso the biggest postseason moment of his career.

The four division series matchups are set, and they will include some potent division rivalries: The Detroit Tigers, who ended the regular season on the heels of the Cleveland Guardians in the American League Central, will have a chance to eliminate them in October. The San Diego Padres, who nearly caught the Los Angeles Dodgers in the National League West, will get a chance to avenge their loss in that race, too. And the NL East rival Mets and Philadelphia Phillies will meet for the first time in postseason history with an NLCS spot on the line. (The New York Yankees will meet the Kansas City Royals in the other division series, and that’s not a bad matchup, either.)

Meanwhile, four once-promising teams are heading home, including the AL West champion Houston Astros and the six-time-defending NL East champion Atlanta Braves. The division series begin Saturday. In the meantime, here are five things we learned from the opening round:

THESE METS ARE DIFFERENT

Year after year, series after series, hopeful season after hopeful season, the Mets built a reputation for conjuring disappointment out of promise. But this year, after a slow start, they played their way back into the playoff race. Needing a victory to secure a postseason spot Monday, they won an instant classic against the Braves. And down two runs in their final inning Thursday, they rallied to beat the Brewers and earn a spot in the division series.

Perhaps more importantly for the sake of momentum, Thursday’s win came when Alonso, in what could have been his last plate appearance as a Met after all but disappearing this postseason, smashed a three-run homer to keep his team’s season alive and write his way into Mets lore in such a way that a winter parting may seem far harder to fathom. If there is a team of destiny, it might just be the boys from Flushing – in the year when their owner Steve Cohen cut back on spending, no less.

GAME 1 REALLY MATTERS

MLB has played 12 best-of-three first-round series since the postseason expanded to its current 12-team format in 2022. The team that won Game 1 of the series won all of them. Game 1 losses are so demoralizing, it seems, that the teams that suffer them have tied these first-round series only twice in three seasons. This year, the Brewers bucked the trend by pushing the Mets to a third game with their come-from-behind win in Game 2 on Wednesday night. The Mets were also involved in the other three-game series, when they forced a third game against the Padres in 2022.

THE AL CENTRAL WAS LEGIT

The AL Central was one of baseball’s most difficult-to-predict divisions, which meant at times it seemed to lack credible title contenders.

The Guardians challenged for MLB’s best record from start to finish in a surprisingly strong campaign. The Minnesota Twins were expected to contend for the division title and did so until a late collapse. The upstart Royals sprinted into contention after a hapless 2023 season, and they would have been the division’s biggest surprise were it not for the remarkable late run of the Tigers.

The relative parity was not, it seems, an indication of mediocrity: The Royals knocked off the 91-win Baltimore Orioles, and the Tigers did something no team had done in the past seven postseasons: They knocked the Astros out before the American League Championship Series. Maybe the 121-loss Chicago White Sox would not have fared so poorly in another division. Then again, maybe they would have.

THE PADRES ARE BACK

Last year, the Padres missed the playoffs after a debacle of a regular season in which clubhouse discontent and on-field disappointment combined to leave General Manager A.J. Preller looking vulnerable in the job he has held since 2014. After years of pushing the perceived limits of its market’s resources, the organization cut payroll, seemingly taking a step back after years of pushing for a title. Instead, it stepped forward.

And in the first test of whether regular season mojo would translate to October, new manager Mike Shildt’s suddenly cohesive Padres beat the Braves without using their ace, Dylan Cease. Even after right-hander Joe Musgrove suffered an elbow injury Wednesday night, the Padres have one of the best one-two starting pitching punches in the tournament with Cease and Michael King. Thanks to two major trade deadline acquisitions, they also have one of the deepest bullpens around. And it looks like the stars they hoped would lift them in Octobers past, Fernando Tatis Jr. and Manny Machado, are ready to do so now. The Dodgers await.

NO EXPERIENCE REQUIRED

Young stars on the postseason stage for the first time have not only looked comfortable on it, they have stolen it. Twenty-year-old Brewers outfielder Jackson Chourio, for example, blasted two home runs in Milwaukee’s series-tying win over the Mets on Wednesday night. He became the youngest player to homer twice in a postseason game since Andruw Jones did it in the 1996 World Series at 19.

Meanwhile, Padres outfielder Jackson Merrill, a 21-year-old rookie, hit an electrifying triple in San Diego’s series-clinching win over the Braves, then made a gutsy retreating catch to help seal a one-run victory in the ninth. In Baltimore, postseason rookie Bobby Witt Jr. drove in two of his team’s three runs in the series and provided noticeably sturdy shortstop defense as Kansas City advanced to play the New York Yankees.

And the Tigers, loaded with players who barely had big league experience before the season, let alone postseason experience, swept the grizzled Astros in Houston, looking undaunted from start to finish.