Stephen Strasburg struck out 12 and picked up his first win of the season as the Nationals defeated the Miami Marlins. (John McDonnell/The Washington Post)

Stephen Strasburg has been more bluntly impressive and produced gaudier statistics than he did Thursday at Nationals Park on a chamber-of-commerce afternoon. But rarely, if ever, has Strasburg been more essential to his team, more assured in his mind-set and more artistic in his craft.

Powered by an obscene change-up and a precise fastball and unbothered by miscues behind him, Strasburg carried the Washington Nationals to 7-1 sweep-sealing victory over the Miami Marlins. Strasburg struck out 12 and yielded one run on three hits in 62 / 3 innings, his first win of the season coming one day after the Nationals’ bullpen exhausted itself for 71 / 3 innings. He dashed any remaining question about diminished velocity with 96-mph aspirin tablets, and he steamrolled ahead after two errors.

Strasburg pitched with finesse more than he threw with power, and he forced the Marlins to react to his pitches exactly as he wanted. He pummeled the strike zone and utilized off-speed pitches. Strasburg retired 14 consecutive batters at one point, induced 17 swinging strikes and threw 27 balls in 98 pitches. He stayed in full command.

“I don’t need to go out there and trick guys, and I don’t need to go out there and be perfect,” Strasburg said. “I just got to attack the strike zone, let my stuff work and get much better results that way.”

Strasburg was staked to the lead by Jayson Werth’s two-run homer in the third inning. In the eighth inning, shortstop Ian Desmond turned a 3-1 game into a rout when he launched the Nationals’ second grand slam in two days, a blast to left-center off Marlins reliever Arquimedes Caminero.

The Post Sports Live crew discusses the most concerning of the Nationals’ myriad early-season struggles – from Harper’s slow start to Zimmerman’s throwing woes and injury concerns. (Post Sports Live/The Washington Post)

Once the ball bruised the red seats, the Nationals (7-2) could turn their focus to another showdown with the Braves in Atlanta. They will enter Friday night in first place, leading the majors in run differential at plus-22, for what that is worth after nine games. Their only losses came last weekend to the Braves at Nationals Park.

“This is the type of ball that we can play,” Werth said. “You’ve got to keep tacking on runs late. These teams in our division, they can hit. So they’re going to be doing the same. But I think night in, night out if we come in here looking to outslug the other team, we’re going to be in good shape.”

Desmond’s slam and dominant relief from Jerry Blevins and Aaron Barrett aside, Strasburg delivered the Nationals’ latest victory. In his first start, the New York Mets tagged him for four runs in the season’s first three innings. His second outing, against the Braves, unraveled after Ryan Zimmerman committed a throwing error.

Between starts, Strasburg discussed with Desmond changes he wanted to make. Neither divulged those plans with any specificity. But Desmond said Strasburg’s confidence in his plan reminded him of veteran pitchers. The start, Marcell Ozuna’s solo homer in the seventh notwithstanding, followed Strasburg’s script.

“To see him go out and execute it today, exactly the way he wanted to change and what he was going to mess with, was pretty good to see,” Desmond said. “That’s maturity. Everyone forgets how young he is. He’s going to keep on getting better and better, and today was proof of that.”

Strasburg, 25, dominated almost exclusively with fastballs and change-ups. For all the hosannas his fastball receives, Strasburg’s best pitch is probably his change-up, and it was at its most sinister and precise Thursday. The pitch starts straight like his fastball, then tumbles down and to his right. It moves like a Slinky on fast-forward.

Against right-handed hitters, it started down the middle and dove at their ankles. Against left-handed batters, Strasburg threw it at their front hip, and it curled back over the inside edge of the plate. Strasburg can sprinkle in sliders and change-ups, but the effect his fastball-change combo has is bedeviling.

“You want to get any hitter in swing mode and get them looking for fastball and throw them something else,” Manager Matt Williams said. “But you have to establish that first, and he did that today. It’s 95-plus, and it’s got a little movement, and then when he can throw his change-up off of it, it looks like a fastball coming out of his hand. And it’s got some depth to it, so you end up swinging over the top of it.”

Strasburg’s change-up by itself is effective, but his approach Thursday turbo-charged it. “It’s been there for the most part all year,” Strasburg said. “It just works a lot better when I attack the strike zone early.”

The Marlins attacked his pitches early in the count, which in prior meetings persuaded Strasburg to nibble. On Thursday, he met their aggression with aggression, pounding first-pitch strikes.

“His tempo was good,” Werth said. “He was throwing strikes. It seemed like he was attacking the zone. With his stuff, when he attacks, it’s pretty tough.”

After Christian Yelich led off with a single, Strasburg recorded 14 consecutive outs, a streak interrupted only when Desmond kicked a grounder with two outs in the fifth. Misplays behind him have rattled Strasburg in the past, even when he was at his best – the slightest nudge, and he fell off the tightrope. After Desmond’s boot, Strasburg blazed a 95-mph over the outside corner to strike out Jeff Mathis.

With two on and one out, Giancarlo Stanton marched to the plate. Having dominated the Marlins all day with his change-up, Strasburg showed faith in his newest pitch. He started Stanton with a slider, which Stanton, perhaps taken by surprise, took for strike one. Strasburg came back with another slider, and Stanton chased it even as it crashed into the opposite batter’s box.

“Any ball he puts in play can take somebody’s head off,” Strasburg said. “So you’ve just got to hit your spots and do everything you can to focus in on each pitch.”

Strasburg had quelled the biggest threat he had faced, and shortly the Nationals would remove tension from the game. Strasburg will miss the Braves, which may have been by Williams’s design — he used an off-day to move Strasburg up in the rotation. On Thursday, when it came time to pitch, he was not only an ace in title.

Nationals 7,

Marlins 1