Bryce Harper follows through on a sacrifice fly during the Nationals’ 7-3 win over the Marlins. He reached 100 RBI for the first time in his career. (Katherine Frey/The Washington Post)

After coming so close, both earlier in his career and earlier Monday night, Bryce Harper lifted a curveball into left field and reached a number he never had before.

The ball was caught by Miami Marlins left fielder Austin Dean, a few paces shy of the warning track, but it was plenty deep enough to score Adam Eaton in the fourth inning. And while it seemed like just another run in the Washington Nationals’ 7-3 win over the Marlins, in a game that carried limited significance for two non-contending teams, it gave Harper 100 RBI for the first time in his seven-year career.

Harper, who will be a free agent this offseason at 25, could be playing his final series in a Nationals uniform at Nationals Park. If that is the case, which his teammates and fans won’t know until winter, Harper’s last week will include a milestone that made a dreary matchup — at the end of a dreary season — worth remembering.

“For me, it’s just going out there, trying to score runs and do the things I can,” Harper said. “If I can get to 100 runs, 100 walks and 100 RBI, that’s pretty cool. I’ll take that any day of the week.”

Monday marked the 30th time this year that the Nationals entered a game with a .500 record. They have not, from 4-4 in April to 78-78 after a loss to the New York Mets on Sunday, been able to shake mediocrity long enough to make this year count. Instead their bats slowed for stretches, their pitching depth was dashed by injuries, health was a problem up and down the roster and, by the time the Marlins arrived in Washington for the Nationals’ final home series, it was entirely too late to change that narrative.

And yet Nationals Manager Dave Martinez has noted, time and again, that a handful of Nationals are “playing for something.” That has meant ace Max Scherzer, climbing toward 300 strikeouts for the first time in his career and vying for a third straight National League Cy Young award against the Mets’ Jacob deGrom and his microscopic ERA. That has meant 19-year-old Juan Soto, battling Atlanta Braves outfielder Ronald Acuna Jr. for the NL rookie of the year award. And it has meant Harper, if only implicitly, because the star outfielder has buried a slow start by producing runs in a way he never has.

He came a few feet from that 100th RBI in the first inning Monday, when Eaton led off first base and Harper ripped a double into the left-center field gap. But Marlins center fielder Lewis Brinson cut it off, sliding to do so, and Eaton stopped at third. Anthony Rendon instead drove in the Nationals’ first two runs with a double of his own, the 42nd of his season and a career high.

Energy was hard to locate after that, given the nature of damp weeknights, the rain-soaked start of this fall and the reality that, no matter what, there will be no playoff baseball this year. Both starters, Stephen Strasburg for the Nationals and Sandy Alcantara for the Marlins, struggled to find the strike zone. Strasburg gave up a run in the first and exited after needing 100 pitches to get through four innings.

But once Harper sent that first-pitch curve into left, and Eaton crossed the plate to make it 3-1, and Harper had finally passed 99, fans rose, ditched their umbrellas for a moment and gave a loud ovation that made the scattered crowd feel a little larger.

“I told him it was a good milestone,” Martinez said after the win. “Hopefully next year he can get it earlier in September and we’re really playing for something. He was happy. The team was happy for him.”

Then the Nationals’ offense, as it so often has the past seven seasons, followed Harper’s lead. On Alcantara’s next pitch, Rendon golfed a two-run home run just over the left field wall. On the pitch after that, Soto smacked an opposite-field home run into the Marlins’ bullpen. That totaled four runs on just three pitches, setting the Nationals up for a runaway win, illustrating how flammable their offense still is and showing how much of a spark rests in Harper’s light brown bat.

If this hasn’t seemed like a typical “Harper season,” against his own towering expectations, it is because of the .245 batting average he carried after Monday’s win. When he was named the NL MVP in 2015, he hit .330 and led the league with 118 runs scored and 42 home runs, and in on-base percentage and slugging percentage. He will not do that this season, falling well short in each of those categories. But he leads the NL with a career-high 126 walks, he has appeared in a career-high 154 games, and now has five more contests to pad his career high in RBI.

“That’s a big accomplishment,” Rendon said. “Especially this year, how he went through his struggles. But he didn’t stay out of the cage. He kept on doing his work. He kept on staying diligent about it, so his work paid off.”

And if these are Harper’s final days with the Nationals, if this really is it, then he also gave a small swath of fans at least one more moment to share.