PHILADELPHIA — By the fourth inning of Monday’s contest between the Nationals and Phillies, the boos from Phillies fans occurred so frequently that they sounded like a built-in stadium soundtrack.

They jeered when the Nationals made contact. They jeered when the Phillies didn’t. They jeered when a new Phillies pitcher exited. They jeered just because they could. All of the jeers proved one thing: The Nationals did nearly everything right in their 13-2 victory over the Phillies at Citizens Bank Park.

“The guys right now, their prep work has been awesome,” said manager Blake Butera, who credited his coaching staff. “Is it going to turn into 13 runs every night? Probably not. That’d be great if it did. At the end of the day, our process has been really good. These guys feel comfortable, confident, endowed when they walk into the box.”

Foster Griffin, making his first career start and first appearance in the big leagues since 2022, pitched five innings of two-run baseball. Griffin utilized seven pitches to keep the Phillies guessing for most of his outing.

His only blip was a fifth-inning two-run homer by catcher Rafael Marchán — the rare moment Phillies fans actually cheered. Griffin got Bryce Harper to ground out to second to end his outing.

“I kind of also didn’t want to walk him to get the crowd back into it even more than they already were,” Griffin said. “At that point, I was like, ‘All right I’m going to go at him with what I know I can get in the zone and what I can attack him with.’”

Yet it wasn’t Griffin’s performance that drew the ire of Phillies fans. It was the Nationals’ hitters and their base running.

The first chorus of boos rained from the stands after the Nationals’ first-inning offensive outburst. James Wood, who opened the game with a walk, reached third on a Luis García Jr. double.

Two batters later, Daylen Lile hit a grounder to second. Philadelphia second baseman Edmundo Sosa threw home and Wood slid and avoided the tag to score. CJ Abrams and José Tena tacked on RBI singles, and Jorbit Vivas added a sacrifice fly to give Washington a 4-0 lead.

Washington (3-1) hit three consecutive singles in the second and tacked on another run on a force out. It seemed wherever the Nationals hit the baseball Monday night, they found a hole in the infield.

Washington finished with 17 hits, 14 of them singles. They didn’t hit the ball hard — only one of their 10 hits off Philadelphia starter Taijuan Walker had an exit velocity over 92 mph. But they also worked counts and drew walks when needed.

“Picture perfect is what we saw tonight,” Butera said. “It’s not always going to go that way, but that’s who we’re going to be.”

When the Nationals made contact, they were also smart on the base paths. They took extra bases. They hustled on routine grounders. They extended innings with their effort.

Washington built a reputation in seasons prior for making poor decisions on the bases. The Nationals’ new coaching staff hoped they’d improve their reaction times. Progress isn’t linear, but the third inning was a sign of growth.

In that frame, García and Brady House hit into what could’ve been double plays. Both beat out throws to first base, allowing the Nationals to score two more runs and extend the inning. The boos only got louder.

“That’s something we’ve worked a lot on with our first [base] coach,” García said through team interpreter Mauricio Ortiz. “We worked on it, especially getting that secondary hop. Things are going well.”

Even in the Nationals’ two-run sixth, Washington executed a play they haven’t properly executed in years. Runners were on the corners. Vivas broke for second base. Tena, at third, sprinted home. Marchán threw down to second base, but Vivas stopped midway to draw Philadelphia into a rundown. The Phillies didn’t have time to throw Tena out.

Eventually, Bryce Harper tagged Vivas to end the inning, but it was too late. The Nationals had tacked on another run. The Phillies fans grumbled to themselves in their seats, but remained relatively quiet.

The final chorus of boos came in the ninth inning when García hit a single through the right side of the infield with the bases loaded. Two runs scored. Many Phillies fans headed for the exits as those who remained showered the home team in the soundtrack of the evening.

“We want these guys to bring effort and energy every night,” Butera said. “That’s something we can control. So to see them out there doing it today, up 10 runs running out balls ... that stuff goes a long way and sets the tone for our group.”