Ian Desmond’s three-run, fourth-inning home run turned a one-run deficit into a two-run lead as the Nats hammer the Rangers on Friday. (Greg Fiume/Getty Images)

Ian Desmond intends to inflict damage every time the bat leaves his shoulder. He swings hard, always. He knows some people insist his success comes when he dials down the vehemence of his stroke. They’re wrong, he says. The difference is perception. When Desmond misses with a violent hack, fans see him corkscrewing into the dirt, nearly falling over. “When you hit the ball,” Desmond said, “people watch the ball.”

In the fourth inning Friday night, the fans at Nationals Park rose from their seats, their gaze fixed on the ball Desmond sent hurtling into the twilight. With the Washington Nationals in profound need of a critical hit, Desmond provided the lodestone of their 9-2 victory over the Texas Rangers, the blow most responsible for snapping a string of six defeats in seven games.

Desmond’s three-run homer into the center field seats turned a two-run deficit into a one-run advantage. Staked to a lead, Stephen Strasburg rebounded from a calamitous second inning and spun six dominating frames, allowing no earned runs, striking out nine hitters, walking only one and overpowering a lineup that came to Washington scalding hot.

Once Desmond returned to the dugout, the hit’s significance showed in his celebration: He kept swinging hard. He stung Randy Knorr’s palm with a vicious high-five, and he continued down the line of teammates.

“Wasn’t expecting that,” Knorr said. “MRI tomorrow.”

“I think he took my shoulder out,” Adam LaRoche said.

“He hit me pretty hard,” Danny Espinosa said.

“I gave a little bit,” Nate McLouth said. “I was able to put a little cushion in my shoulder there.”

The bruising celebration carried a message: Relax. Enjoy. Desmond said teammates, friends and family members had been telling him he needed to loosen up. The demands of the job and the stakes of the game had made it difficult. His homer let them all relax.

“It was a party,” Desmond said. “We’re not having enough fun. People have been making that known to us. Every time you hit one from now on, it’s a party in there.”

The Nationals’ offense built off Desmond’s smash. In the fifth, Denard Span’s eight-pitch at-bat and aggressive base running created a run out of thin air. In the sixth, Manager Matt Williams yanked Strasburg after just 88 pitches, and Tyler Moore crunched a two-run double to left field. In the seventh, Wilson Ramos’s single snuck under Alex Rios’s glove in right, and two more runs scored.

Desmond walked to the plate in the fourth inning with runners on the corners and two outs, the kind of situation that has daunted the Nationals. On Wednesday night, they loaded the bases with no outs in the eighth and failed to score. With runners in scoring position and two outs this year, they had hit .167. Their last three-run homer? April 16, Werth off Jose Fernandez . They were trailing again 2-0.

“The mood was like, ‘Here we go again,’ ” Span said.

Less than three weeks ago, Desmond had been batting .214 with four homers. He changed nothing. He figured if he altered his grip, for example, it would take him 20 at-bats to find comfort. If that didn’t work, he would need to change something, and another 20 at-bats would be wasted. If he stuck to his usual swing, he believed, it would be effective eventually.

And so as he came to the plate, Desmond had slugged .574 since his low point. With a 1-0 count, Rangers catcher Chris Gimenez set his mitt on the outside corner, at Desmond’s knees. Lewis fired a 91-mph fastball over the plate’s median, even with the top of the “20” on Desmond’s uniform. As Gimenez reached for the mistake, Desmond swung hard. The ball landed six rows over the Geico sign.

“Huge moment,” Espinosa said.

“His home run, it just gave us some type of energy,” Span said. “After that, we just piled on.”

Strasburg ensured the homer would hold up after a bumpy start. When things go wrong for Strasburg, it tends to come in unexpected moments and in abnormal fashion. Leoyns Martin hit a soft one-hopper back to Strasburg, weak contact that could have ended the inning. The ball deflected off Strasburg’s glove, bounced off his head and plopped to the turf. Strasburg still had time, but after an awkward lunge, the ball slipped from his fingers.

Strasburg found himself in the familiar position of needing to pitch around an error — this time, his own miscue. Rougned Odor, the youngest player in the majors, rolled a single through the right side, scoring Adrian Beltre for the game’s first run.

As the ball skipped through the infield, Strasburg hopped off the mound and grimaced, seemingly in frustration. But the action concerned the Nationals’ dugout enough for Williams, pitching coach Steve McCatty and athletic trainer Lee Kuntz to rush to the mound. Strasburg glowered at them.

“He was doing some funny things out there,” Williams said. “So I went out there and I asked him. And he got mad at me. So I left.”

“There was no need for them to check,” Strasburg said. “They were just doing their job.”

Lewis, the opposing pitcher, made him less fine. He lined a single into left field, which scored another run.

The knock on Strasburg is he folds when faced with adversity. His final four innings offered a strong rebuttal. He retired 12 of hi final 16 batters he faced, and he squirmed out of a sixth-inning, two-on, one-out jam with a strike out and a pop-up. He had faced few Rangers hitters, and so he trusted Ramos, following his pitch calls.

“They kind of all do the same thing,” Strasburg said. “I’ve got to trust the pitch, just execute it, and I think they’ll get themselves out more times than not.”

The Nationals remained one game under .500, but they had stemmed their recent hemorrhaging. Strasburg was great. Desmond kept swinging hard. And the Nationals realized it is okay to relax.

“Sometimes, we may put too much pressure on ourselves,” Span said. “Sometimes you have to take a deep breath, simplify things and just go out there and have fun.”