Stephen Strasburg pitches six scoreless innings to help guarantee the Nationals will finish at least .500. (Kevin C. Cox/Getty Images)

The Washington Nationals’ season has been over, in practical terms, for about a week. So wondering what could have happened had Stephen Strasburg not suffered so many injuries is a fruitless endeavor. It is time to get through the final three games and start planning for next year.

And Strasburg, who will be entering the final season before free agency, likely will be a centerpiece of a slightly different-looking rotation, carrying over the promise of his outstanding finish. Since he returned from an oblique strain Aug. 8, Strasburg has been one of the best pitchers in baseball.

Although he wasn’t as sharp as his recent outings, Strasburg showed guile pitching under a night of constant drizzle in a 3-0 win at Turner Field on Thursday, a victory that ensured the disappointing Nationals would finish with at least a .500 record. In the final start of his up-and-down 2015 season, he struck out seven and walked one over six scoreless innings, adding another strong start to his final push.

“I learned a lot about myself this year,” Strasburg said. “I’m just going to continue to try getting better every single day.”

That Strasburg finished the season with a 3.46 ERA is impressive given all he endured. His sprained ankle late in spring training was the first in a chain of related injuries, from his neck to his back. When he landed on the disabled list for the first time May 30 with neck tightness, Strasburg had a 6.55 ERA and 45 strikeouts to 14 walks over 10 starts, with the original ankle injury causing a change in mechanics.

“You definitely use your whole body to throw, and when one little thing that’s not necessarily arm related occurs, you really have to figure out if that’s going to alter your evenings,” he said. “I want to compete every single time because I’ve been around long enough that I know I’m not going to feel 100 percent every time. But I’ve got a little more insight on what’s okay and what I shouldn’t go out there with. I learned from it.”

In the 13 starts since, which were interrupted by a month on the disabled list with an oblique strain and a minor back flare-up, he posted a 1.76 ERA and 110 strikeouts to 12 walks. He will finish with an 11-7 record and 1271/3 innings. He pitched around a slippery mound and six hits to hold the Braves scoreless on 104 pitches Thursday, entering the offseason with renewed confidence about his ability when healthy.

“I learned to be more aware of my thoughts out there,” Strasburg said. “There are times in the game when you can kind of let your focus slip just for a split second. And I made it a point to not let that happen, to just focus on each pitch and just let everything I’ve got go on that individual pitch and turn the page.”

Strasburg was boosted by a second-inning solo home run by rookie Clint Robinson, who likely will be a key piece to next year’s bench, and a two-run burst in the eighth inning. Bryce Harper, who is seeking a battling title, snapped an 0-for-13 skid with a sixth-inning single. He finished 1 for 4, and his National League-best batting average sits at .331, holding an edge over second-place Dee Gordon of Miami and his .329 mark. Reliever Felipe Rivero notched his first major league save with a two-inning outing.

“It feels great,” Rivero said. “This year has been kind of a blessing for me.”

Jonathan Papelbon attacked Bryce Harper because he subscribes to the outdated perception that Harper is a young punk who should know his place, says The Post's Adam Kilgore. (Tom LeGro/The Washington Post)

The Nationals will enter next season with a strong foundation for the rotation. Jordan Zimmermann, the longest-tenured member, is expected to depart via free agency. Max Scherzer will be in the second year of his seven-year $210 million contract. Gio Gonzalez will be in the fifth year of his $42 million deal but still possessing options for 2017 and 2018. There’s also Strasburg, who likely will see a raise from his $7.4 million salary through arbitration.

If the Nationals don’t make any offseason additions, that leaves Tanner Roark and Joe Ross to fill the final rotation spots. Of course, there’s also Lucas Giolito, one of baseball’s elite prospects, who could start in Class AAA Syracuse next season and push toward the majors.

Normally, teams will shop players who have one year left of control. The Nationals talked to teams about Strasburg last winter but kept their rotation intact in hopes of contending for a World Series, a plan that backfired with a rough season. He will be needed next season to help anchor the rotation. When Strasburg is healthy, the results are undeniable.

“He’s finished as strong as he could possibly finish,” Manager Matt Williams said.