Stephen Strasburg delivers a pitch against the Diamondbacks. He allowed only one hit in six innings as he improved to 13-5 this season. (DARRYL WEBB/REUTERS)

The debate can subside for the few hours every fifth day Stephen Strasburg occupies the mound, the place he is isolated from talk of innings limits and shutdown days. Soon, in a month perhaps, he will split for winter, his season ended by the Washington Nationals. His starts between now and then can be savored.

Strasburg’s performance took precedence Friday night at Chase Field as the Nationals thumped the Arizona Diamondbacks, 9-1, their seventh consecutive victory. Strasburg allowed one hit, a lonely single, over six powerful innings for his 13th win, even while playing with a sore back. He did not always dominate — he walked four batters and allowed a run. But still, the night posed a wild what-if: If not for an unfortunate delay, Strasburg may have taken a no-hitter deep into the night.

With scoreless innings from Sean Burnett and Ryan Mattheus, the Nationals’ bullpen preserved the one-hitter until Craig Stammen allowed a double and an infield single in the ninth. The Nationals’ only one-hitter since baseball returned to Washington came in 2008, in a game started by Tim Redding. Things are not what they used to be.

The Nationals became the first major league team to 70 wins, pushing the best record in the majors to 70-43. If they go 24-25 in their remaining schedule, the Nationals will win 94 games. The edges around the playoffs, October baseball in D.C., are growing less fuzzy.

“I think we’ve got our blinders on right now, just playing,” left fielder Michael Morse said. “This is uncharted waters for a lot of guys in here. We like what we’re doing. We want to keep doing what we’re doing. We’re to a point where we’re not going to change a thing. We’re just going to keep pushing. I think we like winning.”

Their offense clicked again to give Strasburg ample support. Ryan Zimmerman crushed a two-run homer in the fifth inning off Arizona starter Trevor Cahill, and for the second straight game Morse blasted a baseball so far it appeared gravity had taken a break.

Steve Lombardozzi set up the scorching middle of the Nationals’ order with a four-hit night, including a triple in the third that preceded Bryce Harper’s sacrifice fly. Jayson Werth went 3 for 5 with two doubles and two RBI. Since Werth returned from a broken wrist, the Nationals are 9-0 in games he has played.

“The middle of our order, even when we don’t get hits, we work the count or we walk,” Zimmerman said. “And really, anytime you can get guys on two-through-seven, you have a chance to do some damage. Even when we’re not getting hits, even when we’re not hitting home runs, things like that, I think it gets the pitchers’ pitch count up, it extends the inning. And when you do that, good things happen.”

Strasburg ensured most of the runs were cosmetic. He pumped his fastball mostly at 96 mph, touching 98 at times. Throwing to catcher Kurt Suzuki for the first time, Strasburg fired 73 heaters out of 104 pitches. Nationals coaches have implored Strasburg to rely on his fastball and sprinkle in other pitches. Friday, he obliged, to great effect.

“He just stayed right on the knees,” Manager Davey Johnson said. “He didn’t go up top. Then when he mixes in a change-up, there’s no chance. I love to see him when he pitches that way. When he started cutting it loose, he was really nasty. It was really a great ballgame, and they’ve got a fine offense over there and he shut them completely down.”

Strasburg actually pitched through a measure of pain. The middle of his back had stiffened from travel, sleeping on planes and such, a typical and minor ailment. To end the second inning, Strasburg made a lunging catch while covering first base. The play exacerbated the problem.

“It got a little stiff, especially standing out there for a little bit,” Strasburg said. “It happens. I wanted to go out there and grind through it. I found that when I didn’t try and just go nice and easy, then it kind of didn’t feel so good. I just needed to let it rip, and that’s when I started getting my command back.”

Strasburg struck out six and rarely yielded hard-hit outs. In the second, he whiffed Justin Upton on a diving, 97-mph fastball that Upton swung over, on the black and at the knees.

In the fifth, he struck out Stephen Drew and Aaron Hill back-to-back, both frozen by sliders that curled over the plate. He was at complete ease, except for one strange moment.

Strasburg did not allow hit in the first 32 / 3 innings. He was cruising along in the fourth when Miguel Montero foul-tipped a 1-1 fastball, drilling home plate umpire Dale Scott’s face mask. Scott staggered backward and collapsed to one knee. After a trainer administered a test on him, Scott walked off the field for the night. Third base umpire C.B. Bucknor retreated to the umpire’s room to change into gear for patrolling the plate.

As Bucknor changed, Strasburg dawdled on the mound, playing toss with Suzuki to stay loose. Nine minutes passed before the game resumed. His back stiffened more.

“It was tough,” Strasburg said. “I’ve never experienced anything like that. I hope he’s okay and everything. Unfortunately, it happens sometimes.”

After the break, Strasburg missed badly with two balls, Montero fouled a couple of pitches off and then worked a walk. Chris Johnson followed with the Diamondbacks’ first hit, a hard roller through the left side that scored Upton from second to tie the game at 1.

The delay “really affected him, and it’s my fault,” Davey Johnson said. “I feel bad because I should’ve known it was probably going to take 10 minutes and I let him stand there, and so did all my coaches so I’m going to get on them too for not bringing him in, but it’s my fault.”

Zimmerman picked up Strasburg in the fifth. Lombardozzi hit a one-out single through the right side, and with two outs Zimmerman hammered a sinker at his thighs about a dozen rows deep in left-center field, putting the Nationals ahead, 3-1.

Strasburg bounced back in the fifth, striking out the side. His four walks had pushed his pitch count to 93, but Johnson allowed Strasburg, hitting .343 entering the night, to bat for himself. He grounded weakly back to Cahill, then took the mound for the sixth.

Knowing it would be his last inning, Strasburg made quick work of the Diamondbacks. Jason Kubel lined out and Paul Goldschmidt grounded to short. Upton ripped a one-hopper at shortstop Danny Espinosa, which he blocked with his body. Espinosa scooped the ball and made a rocket throw to first base, ending the inning.

Strasburg pointed at Espinosa as he walked off the field, acknowledging his good play. He had retired the final seven hitters he faced after Johnson’s single. If that foul tip had found Suzuki’s mitt, or even if Johnson’s groundball had tracked to an infielder, Johnson may have faced a controversial decision: to choose caution or to let Strasburg chase a no-hitter?

“I’m going to be still overly cautious,” Johnson said. “It wouldn’t have mattered to me one iota if he had a no-hitter. When it got to 115, 120 pitches, he was gone.”

As it stood, the Nationals were on their way to a laugher.

Morse extended the lead in the top of the sixth with a home run few, if any, other right-handed hitters could match. Cahill threw Morse a 1-0 sinker, and Morse crushed it to right-center field. The ball flew over a 25-foot wall that stood 413 feet from the plate. It traveled 446, according to ESPN Stats & Info, the longest opposite-field home run hit all season.

“The exhibition he’s been putting on in BP, the last couple days, he’s losing more balls,” Johnson said. “I mean, they’re not going in the seats. They’re going in the concession stands.”

Thursday, Morse drilled a home run some 430 feet to left field at Minute Maid Park, one of two homers in that game. Recently, he said, his timing has come back to him at the plate.

“It’s no secret I get pitched in, with sinkers in,” Morse said. “So I’ve been getting my foot down pretty early lately. I’m ready for that fastball.

“I always go by the philosophy K.I.S.S. – keep it simple stupid. I try to make the game as simple as possible. I try to make it as easy as possible, but nothing is ever easy. I try to see a ball up and take a good whack at it.”

Strasburg watched from the first base dugout as the Nationals tacked on three more runs in the ninth inning, forcing the most dedicated fans back home to stay up as 1 a.m. beckoned.

Strasburg was in the thick of another win, strutting with the team on top of the majors. What would come could wait.