LOS ANGELES — The Philadelphia Phillies have existed for more than 140 years, during which time they’ve reached eight World Series and featured some of the most indelible rosters in baseball history.

By at least one measure, though, they’ve never been as dominant as they are right now.

On Monday, after prevailing against the defending champion Los Angeles Dodgers in a tense back-and-forth contest, the Phillies clinched a National League East title earlier than they ever have — on the 15th night of September, with almost two full weeks of regular-season baseball remaining.

It was a product of the New York Mets’ precipitous slide, but also of the Phillies’ surge. They’ve won 11 of 14 games this month and boast the sport’s best record since the start of August.

In other words, they might be peaking at the perfect time.

“We’re a really good team,” Phillies first baseman Bryce Harper said after the 6-5 10-inning win. “I think we’re playing really good baseball right now. Just got to keep going, and keep understanding we have a bigger picture and we have things on our mind that we want to win.”

The Phillies’ latest win, one that secured their third consecutive season with 90-plus victories, came in fitting fashion.

It began with Kyle Schwarber, who clobbered his 53rd home run off left-handed reliever Anthony Banda, who was used as an opener primarily to match up against one of the sport’s premier sluggers. Ranger Suarez pitched effectively thereafter, providing six innings of three-run ball to continue a run of dominance from the Phillies’ three left-handed starters. The rest of the group followed by continually punching back.

After Mookie Betts tied it with a solo homer in the seventh, Harper answered with his own in the eighth to put the Phillies back on top. After Andy Pages tied the game once more with a home run in the ninth, the Phillies manufactured a run in the 10th, culminating in a hard-fought sacrifice fly from J.T. Realmuto. And after the Dodgers loaded the bases with one out in the bottom half of the inning, David Robertson somehow wiggled out of trouble, getting Miguel Rojas to fly out and Max Muncy to ground out to seal the 13th division title in franchise history.

The Phillies have won back-to-back NL East titles and sit 5½ games ahead of the Dodgers for the No. 2 spot in the NL and thus a first-round bye.

“There’s a lot of confidence in this room,” Realmuto said. “We all believe in each other. We think we’re going in a good direction.”

The Phillies boast a major-league-best 29-14 record since the start of August and have shrugged off any adversity they’ve faced since then. Zack Wheeler landed on the injured list with what became a season-ending blood clot near his shoulder on Aug. 16, and since then the Phillies’ three lefty starters — Suarez, Cristopher Sanchez and Jesus Luzardo — have combined to go 9-1 with a 2.55 ERA.

Trea Turner and Alec Bohm, making up the left side of their infield, both landed on the IL last Monday, and the Phillies proceeded to win six consecutive games, including a four-game sweep of the Mets. Standout reliever Jose Alvarado, already ineligible for the playoffs after testing positive for a performance-enhancing drug, suffered a forearm strain last week, but the bullpen has found a way nonetheless.

The core of Harper, Schwarber, Turner, Realmuto, Bryson Stott and Brandon Marsh has produced, but a more unheralded group consisting of Otto Kemp, Max Kepler, Weston Wilson and Edmundo Sosa has also contributed. A trio of midseason additions — Robertson, outfielder Harrison Bader, closer Jhoan Duran — have further buttressed the roster.

“I think our depth is as good as it’s been,” Realmuto said. “And as much as it’s tough to lose a guy like Wheeler, we have so much starting-pitching depth. They’re really good, they give us innings, and the back end of our bullpen is, in my opinion, as good as it’s ever been with the Phillies. That really matters in the postseason, being able to get those outs in the eighth or ninth inning and have confidence in your guys. That’s a huge deal.”

The Phillies have made the playoffs each of the past three years but have come up short in their quest to claim the franchise’s first title since 2008. In 2022, they were defeated by the Houston Astros in the World Series. In 2023, they ran into a red-hot Arizona Diamondbacks team in the NL Championship Series. In 2024, the Mets dispatched them in four Division Series games.

In some ways, this year feels more pivotal than all of them. Realmuto, Schwarber and Suarez are scheduled for free agency in the offseason. The overall core is aging. This next month, outside evaluators believe, might represent the best chance for this group to solidify its greatness with a championship.

That journey began Sunday afternoon, while stuck on an airplane that faced mechanical issues while attempting to leave Philadelphia. The players found out then that, by virtue of the San Francisco Giants’ loss to the Dodgers, they had clinched a spot in the postseason. They abstained from celebrating, landed in L.A. at around 2 a.m. and hoped to revel in a bigger accomplishment.

Roughly 20 hours later, it happened. The Phillies’ traveling party slipped into commemorative T-shirts and ventured into Dodger Stadium’s small visiting clubhouse for the type of alcohol-and-cigar-infused celebration that has become all too familiar for so many of them. Rob Thomson, in his fourth year as manager, gathered his players, held an uncorked champagne bottle in his left hand and praised the way they overcame adversity. He then turned to Realmuto and asked, “How many we got left, buddy?”

“Whatever the hell it takes,” Realmuto yelled in response, kicking off the revelry.

The Phillies hope it’s many more.

“Every team that we’ve had in the last couple years, we’ve been really good,” Harper said. “It just hasn’t happened. We just haven’t finished with a win, and we’ve got to do that.