WASHINGTON — Daniel Hudson stood on the outskirts of the writhing, soaking mob in the middle of the Washington Nationals’ clubhouse. He watched his teammates dump beers on one another — celebrating the National League pennant — as he grinned, nodded to the music and held a Budweiser.

Hudson loves these guys, and he loves having fun, but he was still unwinding from “probably the highest-leverage [situation] I’ve ever been in in my career.”

The Nationals had summoned him in the eighth inning of Game 4 of the NL Championship Series on Tuesday. There was one on with two outs. They had a three-run lead.

Hudson never wanted this; he never wanted to close. He had expressed this before. And there on the mound, with more than 43,000 screaming fans, with the chance to secure a sweep of the St. Louis Cardinals, Hudson felt seized by the moment. He felt adrenaline and anxiety. His control slipped.

But now it was over. They had the trophy. They were going to the World Series, so Hudson allowed himself to admit the truth.

It’s his stuff. It’s the vibe. It’s the way the innings seem to unfold. All of it unnerves Hudson because, although he has been the Nationals’ best reliever since they acquired him at the trade deadline — posting a 1.44 ERA in 25 regular-season innings — everyone in baseball understands the ninth inning is different.

Pitching coach Paul Menhart, manager Dave Martinez and former closer Sean Doolittle all nodded solemnly when they discussed the mental toughness it takes.

This pressure is still relatively new to Hudson. He didn’t come up pitching the end of games; the right-hander was once one of baseball’s best young starters with the Arizona Diamondbacks. But back-to-back Tommy John surgeries derailed his career and turned him into a journeyman.

The 32-year-old started this season with the Los Angeles Angels, but they released him. He latched on with the Toronto Blue Jays and posted a 3.00 ERA in 48 innings, enough to draw mild interest in a thin trade market.

The Nationals acquired him as one of three main pieces to revamp their historically bad bullpen. They used him as the fireman, the pitcher they would deploy with runners on base or against the toughest part of the lineup. He succeeded right away, stranding nine of his first 10 inherited runners. Then he became the team’s most important reliever.

Doolittle suffered a knee injury around that time in mid-August and landed on the injured list. Martinez needed to replace him, so he tapped the hot hand. Hudson protested, but the manager held firm.

“I know the ninth inning’s a different beast,” Martinez said. But he told his relievers, “Don’t worry about what inning it is; just get outs” — because he “wanted them to understand that’s the way they need to approach it.”

Hudson remained hesitant because he thought his stuff didn’t suit the role. He threw too many strikes and allowed too much contact; he relied on a four-seam fastball or slider 90 percent of the time; he didn’t have “that big, sweeping breaking ball that lot of [closers] have.”

And something went haywire every time he pitched the ninth, he noted, such as broken-bat singles or bloopers. Hudson called his success at stranding runners “fluky.” He repeated that the team needed Doolittle in the ninth inning to get where it needed to go.

Doolittle returned to the team in early September, but he wasn’t himself. No one else in the bullpen had stepped up, so Martinez kept riding Hudson. Doolittle wasn’t surprised his teammate didn’t like the role.

“There’s a lot of guys that don’t, to be honest,” said Doolittle, who acknowledged “there’s no gray area” in closing.

In Game 4 against the Cardinals, the situation unraveled quickly. Hudson hit the first batter and walked the second to load the bases. Pinch hitter Matt Carpenter was the go-ahead run.

Hudson pounded the strike zone away and, on a 2-2 fastball, got Carpenter to ground out to second base.

“The adrenaline and the energy in the stadium got to me a little bit,” said Hudson. “I was just throwing in that eighth inning, and I got away with it.”

After the eighth inning, he felt changed on the mound and stopped hurling pitches. He executed them. He threw 10 fastballs, and his last one, belt high and away, got Tommy Edman to lift a fly ball to center field.

Victor Robles squeezed the final out. Hudson threw his glove in the air and leaped into the arms of his catcher. It was unbridled joy and presented a paradox that, even later in the clubhouse, he seemed unsure how to reconcile.

“I hate closing,” Hudson said. “But that’s the best feeling in baseball.”