WASHINGTON -- July 31, 2023, was an important date in DJ Herz’s young baseball career. It was the day the left-hander was traded to the Nationals from the Cubs in the Jeimer Candelario deal as a Double-A prospect.

Aug. 31, 2024, was just as significant. It was the first time he faced his former organization -- on Saturday, as the starting pitcher for the Nats.

“I was trying to keep my cool, but I knew I was going to be a little bit more pumped,” Herz said. “I’ve always been a pitcher like that. If I’ve got a reason, I’m going to give a little bit more. I kind of felt that.”

Herz, 23, did not allow a hit until the fifth inning in the 5-3 loss at Nationals Park. He swiftly worked four frames -- facing a total of 13 batters -- before running into traffic on the bases. Herz delivered 4 2/3 innings on 87 pitches (55 strikes), with two walks and five strikeouts. All four runs and three hits came in his final inning.

“The first inning, he came out and he threw the ball really well,” said manager Dave Martinez. “Then he had one inning where he just got the ball up a little bit. We tried to get him out of that inning, he couldn’t get it. He threw one changeup right down the middle that cost him a couple runs. But overall, I thought he threw the ball good.”

Herz was selected by the Cubs out of high school in the eighth round of the 2019 Draft. Two years later, he was named their Minor League Pitcher of the Year. Herz was ranked as the Cubs’ No. 16 prospect, per MLB Pipeline, when he was traded. The Nats added him to their 40-man roster last fall ahead of the Rule 5 Draft. Herz began this season in Triple-A and earned his Major League callup on June 4.

Looking out from the mound on Saturday, he saw familiar faces on both sides of the field.

“It definitely means a lot extra because that’s the team you grew up [with], that’s the team that kind of got you to the man you are today, and they helped me develop a lot into that type of pitcher,” Herz said. “It was weird seeing some of the other guys, like Pete [Crow-Armstrong], who I went through the system with. We gave each other a good smile, and it was cool.”

Herz opened the game by striking out Ian Happ with a 96.5 mph fastball. He retired the side on 11 pitches by getting Dansby Swanson to line out and Seiya Suzuki to ground out.

“I think the key was the first out,” Martinez said. “Getting that first out right away kind of slowed him down a little bit.”

In the second inning, Herz induced a ground out to Cody Bellinger before issuing a walk to Isaac Paredes and advancing him to second on a balk. But he locked in to get Michael Busch to ground out to second base in a full count, then catch Nico Hoerner looking on an eight-pitch 95.8 mph fastball.

“When I’m in the zone, that’s all I need to worry about,” said Herz.

Herz swiftly delivered another 11-pitch, 1-2-3 inning in the third. After Crow-Armstrong flew out to center field, Herz fanned Christian Bethancourt and struck out Happ in an at-bat that included a knuckle curve, changeup, fastball and slider.

“His changeup was working, his spin was working, his heater had a little bit more oomph on it than normal,” said catcher Drew Millas. “... His stuff was playing today, and he used it well.”

Herz, who was looking to complete at least five innings for the third start in a row, allowed his first hit of the game when Paredes singled on a slider into left field to open the fifth. Herz issued a walk to Busch and a single to Hoerner to load the bases with no outs.

With an 0-2 advantage in the count, Herz surrendered a sacrifice fly to Crow-Armstrong that put the Cubs on the board. Bethancourt lined a single into center field, where Jacob Young committed a fielding error and Busch tied the game.

Herz’s final at-bat of the day was inducing a ground out by Happ, on which Hoerner scored the go-ahead run. Herz was replaced by Jacob Barnes, and he was charged with the run when Bethancourt scored on a Swanson double.

“I think I was still pitching the same,” Herz said of the fifth inning. “Paredes finds a way to get one down the line, just something you can’t control. There were times where I got 0-2 or 1-2, and I think I was trying to maybe chase instead of just staying in the zone and not nibbling. I think that came back to get me, especially in that last inning with Busch. I can control that walk.”

When Herz turns the calendar to September, there will be another series circled. The Nationals travel to Chicago for their final road trip of the season, Sept. 19-22.

“I know I’ll get them again at Wrigley,” Herz said.