Bryce Harper gazes at his seventh inning sole home run that landed 431 feet from home plate in the bushes in center field at Petco Park. (Denis Poroy/GETTY IMAGES)

Stephen Strasburg reached something resembling a crossroads Thursday night, a game that felt more substantial than a typical mid-May start. He climbed the mound at Petco Park after four days of pointed questions about his mental strength. His Washington Nationals had lost two straight. Strasburg pitched for the first time in his hometown, not far from West Hills High and San Diego State. His father, Jim, milled behind the batting cage pregame, and 50 friends and family members sat in the seats.

The Nationals did not need Strasburg to be brilliant in a 6-2 victory over the San Diego Padres, Strasburg’s first win since opening day and a triumphant homecoming. They only needed him to be tough and resilient, to squelch mistakes rather than let them devour him whole. The Nationals will want more of Strasburg in the weeks, months and years to come, because that is what his talent demands. For one night, they could revel in an error leaving Strasburg at a key juncture, and then watching him lift his head, point to his third baseman and say, “I got you.”

In the 54th start of his career, Strasburg pitched into the eighth inning for the first time. He mowed through the eighth in 10 pitches despite a walk. His 117th and final toss — a fastball, 93 miles per hour — turned into a ground ball to second base for an out. “All right,” Strasburg thought. “This is what it feels like.” He had allowed two runs (one earned) on three hits and three walks, striking out four and lowering his ERA to 2.83.

For Strasburg, calm glances and deep breaths replaced slumped shoulders and eye rolls. He focused, he said, on “better mound presence.” Over the past week, he had studied Jordan Zimmermann and Clayton Kershaw and wanted to mimic their hard-charging, straight-ahead demeanor.

“I’m trying to go out there and let your teammates feed off of your confidence, and when one thing doesn’t go the way you thought it would, to not let it affect the next pitch,” Strasburg said. “I think that’s when I’m most successful, when I kind of block out all the stuff, and I just focus on throwing each pitch and focusing on the next one.”

The Post Sports Live crew debates whether Stephen Strasburg’s recent pitching struggles are all in his head. (Post Sports Live)

Strasburg’s offense finally bulwarked him with runs, giving him a 5-0 lead in the fifth inning as Ryan Zimmerman and Adam LaRoche drove in four runs. Bryce Harper, back in the lineup three days after he tested the structural integrity of the Dodger Stadium, fence, would add an insurance run in pure Harper fashion — with a 431-foot homer into the bushes beyond the center field fence.

Strasburg still had to work to protect the lead, partly of his own making and partly because of failing behind him. And he did protect it.

“He had a different mentality tonight, where you’re not letting the little things bother you,” catcher Kurt Suzuki said. “Guys hit the ball or had good swings off him, it was more, ‘Hit this one.’ It wasn’t, ‘Oh, no, what do I do now?’ It was that bulldog mentality, that horse mentality — ‘I’m going to come right at you. Here it is. Hit it.’ ”

Equipped with his biggest lead of the season in the fifth inning, Strasburg yielded a double to Jedd Gyorko and walked Alexi Amarista. With one out, mammoth pinch hitter Kyle Blanks smoked a one-hopper down the third base line. Zimmerman made a diving stop that saved at least one run, rose to his feet and whipped a submarine throw toward second, over Steve Lombardozzi’s head.

The error, Zimmerman’s eighth this year, loaded the bases with one out. Strasburg possessed the ability to work around this, to escape the inning with a comfortable lead. Did he possess the resilience?

Strasburg’s season had not been a pure disaster. His 1-5 record stood in contrast to a 3.10 ERA — better than last year — and 51 strikeouts in 49 1 / 3 innings. Only three National League starters had received less than his 2.76 runs of support per game. It was not his pitching that surprised observers and teammates. The way he responded to adversity, though, had disappointed.

In his last start, Strasburg cruised for four innings and quickly retired the first two batters in the fifth. Then Zimmerman made a throwing error, and Strasburg crumbled. The next five batters reached, and a superlative start had yielded to a four-run trainwreck. Davey Johnson, his manager, said Strasburg needed to push mistakes behind him. Wilson Ramos, his catcher, told him, “You need to fight.”

Now, with the bases loaded and a 5-0 lead, Strasburg needed to fight.

“I was going to go out there,” Suzuki said. “I was thinking about going out there and talking to him. Once he got the ball back, he looked at Zim and said, ‘I got you.’ Once he did that, I turned around and went back to home plate. Because I knew he was going to do it.”

He started Everth Cabrera with a curveball in the dirt, and Suzuki smothered it with a crucial block. Cabrera grounded out to first, enough to score a run but also enough to stop the bleeding.

Up came Will Venable. Strasburg fired a changeup, moving all night like a one-winged butterfly, for strike one. Venable fouled off a fastball for strike two. Suzuki called for another changeup, and Strasburg twirled one of his best. Venable swung and missed, haplessly early.

Strasburg reached the dugout steps at the same time as Zimmerman. Strasburg stuck up his palm, and Zimmerman slapped it hard with his glove.

“I was just happy we got out of the inning,” Zimmerman said. “Stephen threw good tonight. He attacked.”

The Nationals still led by four runs. Strasburg had not allowed the game to slip away after an error — a low bar, but still one he needed to cross.

“It was good to play behind him with the kind of confidence he had,” LaRoche said. “He gave up a run. He didn’t get down. He didn’t worry about it. He went right after the next guy. He looked a little more aggressive to me than he has in the past, as far as fastballs for strikes — if they hit ‘em, they hit ‘em.”

Throughout the game, Strasburg could hear fans yelling “Welcome home!” and “Go Aztecs!” “I’m just glad they remembered me,” he said, smiling. He felt no nerves, only embraced.

“It’s easy pitching in front of a lot of loved ones,” Strasburg said. “They just want to go out and support you either way.”

He had last pitched here in college, against UC-Davis, a game he remembered with ire because he had lasted only six innings. That had become a typical occurrence in the majors. On this night, he walked off the mound after the seventh inning and didn’t see Johnson standing on the top step.

Last year, when the Nationals placed Strasburg on an innings limit, Johnson lifted him one inning early in an effort to elongate his season. This year, Strasburg wants to be an ace. Johnson will cultivate the possibility.

“This year,” Johnson said, “I’m going to be pushing him.”

After Rafael Soriano closed out the Padres, the Nationals in the dugout poured on to the field to line up and shake hands. Strasburg hopped up the stairs first, and he led them.