NEW YORK -- The Nationals’ afternoon at Citi Field began with a 31-year-old pitching in his first Major League game since 2015. The second game of the doubleheader saw a 26-year-old rookie embracing a sudden influx of relief appearances and a newly appointed closer surrender a walk-off home run.

Kyle Finnegan’s loss and Gabe Klobosits’ sharp late-inning outing in the Nationals’ 5-4 loss in the second game, paired with Sean Nolin’s start in the opener (a 4-1 loss), were snapshots of the new roles following the roster overhaul at the Trade Deadline.

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The Nationals, who scored three runs in the top of the seventh to tie the game, have dropped nine of their past 10 games.

“It’s going to be a learning process for a lot of these guys,” Nationals manager Dave Martinez said. “And that’s what you’re seeing.”

Finnegan allowed a solo shot to the reigning Home Run Derby champion when Pete Alonso walloped a 94.9 mph sinker to left-center field to crush the Nationals’ comeback attempt. The 28-year-old right-hander has stepped into the role of closer following the trades of Brad Hand and Daniel Hudson.

“You definitely want to get beat with your best stuff there, your No. 1 pitch, your go-to stuff,” Finnegan said. “I feel like I threw my best bullet there, and he got it. That’s part of the game. He made a great play for his team, and I’ll be ready to go tomorrow.”

When the Nats swapped eight veterans for 12 young players last month, it was clear which players remaining on the team -- like Finnegan -- could see increased action. Since then, Minor League callups have added their names to the mix.

Klobosits, the 26-year-old rookie, had been working his way toward pitching for the Nats since he was selected by the organization in the 36th round of the 2017 Draft. He rose to the Majors after beginning this season in Double-A, and he is seeing the work he has put in since Spring Training translate into results on the mound.

“Really, just consistency with my offspeed,” Klobosits said pregame of his most notable improvements. “I feel a lot more comfortable to throw a slider in any count, like I did last night, 3-2 count, two outs, got out of a jam. The split, I feel comfortable throwing to lefties and righties now. Really, just attacking guys; don’t be scared.”

After making his big league debut on July 30, Klobosits has received seven calls to the bullpen. On Thursday, the 6-foot-7, 270-pound right-hander threw one frame without allowing a hit, run or walk. He struck out Alonso in the fifth inning of a seven-inning game. His fastball reached 95.9 mph.

“He’s doing really well, and he’s a guy that wants the ball every day,” Martinez said. “He always says he’s good, which is awesome. … The thing about him is that he pounds the strike zone. He’s been doing that so far, so I like that.”

Nolin stands out from the group of Minor Leaguers because of his previous experience. The left-hander had pitched three seasons in the bigs with the Blue Jays and Athletics before playing last year in Japan. Nolin was thriving with the Triple-A Rochester Red Wings this season (3-3, 3.80 ERA, 11 appearances) when the Nationals selected his contract on Wednesday and tabbed him to start the opener of the doubleheader. He allowed eight hits (one homer), four runs and no walks with two strikeouts in three innings (51 pitches, 37 strikes).

“I thought he threw the ball fine,” Martinez said. “He talked a lot about his cutter not being as effective. It didn’t have that bite that he typically has. But I thought he held his own and he did well.”