Tanner Roark struck out 11 Diamondbacks in the Nationals’ 4-3 win over Arizona. (Jennifer Stewart/Getty Images)

The Washington Nationals have played just fine this month, well enough to move their division lead into double digits, well enough to lend credibility to the belief that it will not shrink much from there. But Saturday night’s 4-3 win over the Arizona Diamondbacks highlighted a positive portion of their circumstances lost in the day-to-day minutia.

This team, the one that is doing just fine and has won 8 of its last 11 games, has a chance to be far better in the next two months than it was in the last two. Reinforcements, like the ones who got the hold and save Saturday — Ryan Madson and Sean Doolittle — have already come. More, in the form of injured players turned healthy, or struggling players rejuvenated, are on the way.

One of them arrived in force Saturday evening, when Tanner Roark worked seven masterful innings in which he allowed two runs and struck out 11 batters — his third career game with double-digit strikeouts and first this season. Roark had not been the same this season as last, but he has now allowed two earned runs in his last 13 innings.

“He doesn’t look worried. He was looking worried before,” Nationals Manager Dusty Baker said. “. . . It looks like Tanner’s back, big time.”

Roark had a lead before he took the brittle Chase Field mound Saturday. Bryce Harper gave it to him, obliterating a two-strike offering from Diamondbacks starter Anthony Banda, a left-hander who was making his major league debut.

The Diamondbacks tied the game against Roark in the first, though they nearly didn’t. Chris Iannetta’s RBI double was a few inches away from being a harmless foul ball.

But other than that double, Roark looked like the near-all-star he was in 2016 — if not better. His secondary stuff broke and landed for strikes. He threw his change-up wherever he needed it. His curveball bit and got swings and misses. His slider enticed Diamondbacks hitters to reach out of the zone. Roark had not struck out eight men in a game since late May. He struck out that many in the first five innings Saturday evening.

“It was something that started feeling good,” Roark said. “[The curveball] is probably my second-best pitch, and it felt good today. You got to throw it and keep it down and not try to make it break. That’s how I’ve been feeling . . . with every pitch.”

Roark never could say exactly what ailed him early this season. At times, when he could not click his mechanics into place, he seemed frustrated to the point of anger and called himself “pathetic.” While the results did not improve much in June, his post-start demeanor did. After and during his last three starts, in which he has struck out 18 men in 18 innings and allowed five runs, Roark has oozed confidence.

“It’s a good feeling when one of your guys has that feeling. You get that feeling,” Baker said. “The whole team gets that feeling. So it’s great to have Tanner throwing the ball there.”

Until the top of the sixth inning, Roark needed every ounce of command he could find, because the rookie Banda was unfazed by Harper’s homer and had held the Nationals to one.

Chris Heisey wasn’t supposed to be in the Nationals’ lineup Saturday. But Ryan Raburn’s grandfather died, and the veteran was, as his manager put it, “shook up.” Raburn will leave the team for bereavement leave Sunday, and catcher Pedro Severino will take his roster spot. Heisey took Raburn’s place in the lineup Saturday night.

In the sixth, Heisey pulled a pitch into the left field corner for a triple. Baker later revealed Heisey hurt his groin on the play, and the depleted Nationals outfield corps might lose him, too — though no one could say for sure immediately after the game.

With Heisey on third, Harper doubled the opposite way, his second hit and RBI of the game, which already marked his 15th consecutive game with a hit — a career high.

Ryan Zimmerman followed that with his second hit of the night, a double to center — the 361st two-base hit of his career, which pushed him past Tim Wallach for most in Expos/Nationals history. Anthony Rendon drove home a run with an infield single to push the Nationals’ lead to three.

That middle of the order squandered a chance to add to the lead in the seventh, when Jorge De La Rosa struck out Harper and Zimmerman with the bases loaded. At times this season, missed opportunities to take out insurance policies felt like bad omens, foretelling the loss of a late-game lead that could have been bigger.

But this bullpen is better now.

Madson worked around a one-out double to throw a scoreless eighth for the second straight night. Doolittle relieved him and found adventure for the second time in two Nationals outings when a leadoff walk and a Rendon error put the tying run aboard with nobody out. But Doolittle got out of it and earned his second save in those two chances.

“Madson’s been great for us. And Doolittle, seeing him come over and do the things he’s doing, he never panics and it’s great to see,” Harper said. “. . . hopefully get one more guy in that pen and have a three-headed monster.”

The Nationals did not have the good version of Roark, or late-inning options like Doolittle and Madson as they climbed 20 games over .500 initially and built this lead in the National League East — a fact that can be looked at in one of two ways. The first would be to think of what might have been. The second would be to consider what could be.