Washington Nationals starter Stephen Strasburg allows a home run to second baseman Scooter Gennett in the first inning en route to a 4-2 loss to the Milwaukee Brewers. (Toni L. Sandys/The Washington Post)

For his first act of the season’s second half, Stephen Strasburg remained a pitcher of immense talent with incongruous results, a strange mix of dominance and vulnerability. Either hitters cannot hit his pitches at all, or they smear them. He’s hard to hit and maybe harder to figure out.

In the Washington Nationals4-2 loss to the Milwaukee Brewers on Friday night, Strasburg submitted one of his most maddening performances to date. The statistical concoction Strasburg produced was something akin to random puzzle pieces that didn’t fit together. In 98 pitches over seven innings, Strasburg struck out nine — pushing his league-leading total to 158 — and issued only one walk. His excellence was undeniable.

But the Brewers lashed seven hits, two of them home runs, and scored four runs in the first three innings. Baseball statisticians continue to wait for Strasburg’s overall results to catch up with his peripheral numbers — his strikeout and walk totals suggest he should be having one of the best seasons in the majors. Yet it’s not happening, and the loss Strasburg (7-7) suffered put the Nationals back in second place, a full game behind the Atlanta Braves.

“I’d say the fastball command has been pretty good for the most part,” Strasburg said. “Maybe I’m throwing too many strikes. Maybe I need to be more effectively wild.”

Bryce Harper unveiled an overhaul of his batting stance and went 3 for 4 with a ninth-inning homer off Francisco Rodriguez. Still, the Nationals’ offense offered scant support, spending the night creating opportunities against right-hander Kyle Lohse and then flushing them. The Nationals battered 11 hits, but they went 1 for 10 with runners in scoring position, stranded seven runners and grounded into two double plays. Lohse allowed one run over seven innings, scattering hits and recording only three strikeouts.

“It’s baseball, dude. Sometimes that happens,” Manager Matt Williams said. “It’s a credit to their pitching. And it’s a question of us not taking advantage of the opportunity tonight, but that’s why we play tomorrow.”

The fans at Nationals Park rose to the occasion during the night’s most important moment, one that had nothing to do with the outcome. With two outs in the second, Brewers shortstop Jean Segura walked to the plate for his first at-bat since July 11, the day his 9-month-old son died in the Dominican Republic. The crowd showered Segura with warm applause. Segura lined out to center, and on his way to the dugout, both Ian Desmond and Harper patted Segura on the back.

“I feel amazing how the people care about the baseball players,” Segura said.

As for the game, the Brewers jumped out to a 4-0 lead after three innings, and the Nationals never recovered. The best thing a pitcher can do is pile up strikeouts and limit walks. Strasburg does both as well as any starter. Hitters rarely put the ball in play against him, but when they do, it happens at inopportune moments or with considerable force.

Strasburg has 5.85 strikeouts per walk this season, a ratio that portends enormous success. But he also has allowed 9.1 hits per nine innings, two more than his career average before this season. When Strasburg pitches, hitters either flail at his stuff or destroy it. He could be suffering from rotten luck on balls in play, or he could be making too many mistakes over the heart of the plate with his fastball or perhaps a combination of both. Either way, the hits have piled up. His 3.55 ERA is hovering just below the league average of 3.69.

“For Stephen, I think it’s fastball command,” Williams said. “We saw the home runs were fastballs that weren’t where he wanted to throw them. With any club, especially with a club like this that hits a lot of balls over the fence, you can get in trouble that way. But when he does have fastball command and spots his fastball, then everything works off of that.”

The Brewers struck early. The previous time Strasburg faced Scooter Gennett, the second baseman blasted a grand slam in late June in Milwaukee. As the second batter of the second half Friday night, Gennett rocked a solo homer over the right field fence. In the second inning, Khris Davis crushed a 97-mph, 3-2 fastball to right for an opposite-field homer that made it 2-0.

Harper returned for the second half with a new batting stance, a change he revealed Friday afternoon during batting practice. Harper made three changes. He stood upright with less bend in his knees. He held his hands lower, level with his chest. He relaxed his left elbow so it pointed at the ground behind him.

The overall effect made him calmer in his actions. Harper had been “jumpy” upon his return from the disabled list, Williams said. The new stance seemed designed to eliminate the anxiousness, to allow Harper to stay back and wait on pitches.

“I just felt comfortable, and that’s the main thing,” Harper said. “Going forward, I’m just trying to have some fun and relax a little bit.”

Harper had been working on standing taller and moving more gently before the all-star break. When he returned for a team workout Thursday, hitting coach Rick Schu saw Harper had turned the change from a gradual process to a full alteration.

“He gets that easy release to the baseball,” Schu said. “He just has a lot less tension in there. He’s staying tall and downhill. Stack and jack.”

In his first at-bat, Lohse threw Harper a 1-1 slider, and he blistered a single to right field. Ryan Zimmerman zoomed from first to third, and with no outs the Nationals had runners on the corners.

The Nationals botched the rally without scoring even one run. Desmond popped foul, and Wilson Ramos grounded into a 6-4-3 double play. They compounded the wasted chance the very next inning.

In the third, Strasburg recorded two quick outs. He walked Gennett, keeping the inning alive. Ryan Braun scalded a double into the left field corner. Aramis Ramirez hit a flare to right field, a play many right fielders would make. Jayson Werth broke quickly and charged hard, but he could not reach the ball before it plopped to the turf. The Brewers had taken a 4-0 lead.

“That was the one that was really frustrating,” Strasburg said. “You’re going to give up homers in this game. As long as they’re solo, you’re going to be ok. It’s not much I can do there except make a better pitch.”

The Nationals chipped at the lead with Desmond’s RBI single to center in the fourth inning scoring Zimmerman. Strasburg did not allow another run, the kind of performance he is capable of. The damage had already been done, the kind of results the Nationals are still trying to figure out.