Jayson Werth celebrates with Ryan Zimmerman after scoring in the fifth inning. (Greg Fiume/Getty Images)

No one marched out to the mound to retrieve Stephen Strasburg from the Washington Nationals7-4 win over the Miami Marlins on Sunday. He left quickly and quietly, done after four innings, not emerging for the fifth because of upper-back discomfort.

Manager Matt Williams was unemotional as he reported the news after the game. He said the Nationals removed their most recent ace so he wouldn’t alter his mechanics and cause further damage. They have seen that happen earlier this season. “Can’t go there,” he explained.

The postgame clubhouse was unemotional, expressing regret for another teammate struggling with something. That list has been long and varied this season.

Strasburg himself spoke calmly, matter-of-factly, sticking to script: He will get treatment, and he hopes to make his next start. Injuries are routine now, a seemingly daily occurrence unusable as an excuse in a playoff push.

“We don’t have a choice,” said Clint Robinson, one of the unexpected contributors the Nationals have required all season and who homered for the second straight game. “We’re here trying to win ballgames. We don’t have time to sit there and try to get comfortable, try to massage our egos and all that kind of stuff. We’ve got to go out and win ballgames.”

The Nationals have gotten back on track, but is it enough to overtake the Mets and win the division? (Post Sports Live/The Washington Post)

Robinson hit his first career pinch-hit home run in Sunday’s win, in which all eight starters and two pinch-hitters — Robinson and Matt den Dekker — chipped in with hits. After a season of waiting to be whole again, after a few weeks of readjusting to being that way, these Nationals are now the team they will be in September. No reinforcements are coming to save them now. If they are going to come back in the National League East, these starters and bench players must be the ones to do it.

“We’ve got a long way to go, a tough three-game road trip to St. Louis. We need to keep winning series, keep winning ballgames to give ourselves a chance,” left fielder Jayson Werth said. “I don’t think anybody in here has given up or anything like that.”

On Sunday, those Nationals, still without Yunel Escobar for a day or two more, overcame an early deficit and survived Strasburg’s early exit. They earned their fourth straight series win in the process but stayed 51/2 games back in the division because the New York Mets also won.

Strasburg struggled for the first time this month, unable to settle himself, gone after four innings, four runs and 60 pitches. His velocity, which had been in the high 90s during his recent stretch of dominance, sat at 93 to 96 mph.

His pace and body language, both determined and confident since he returned from the disabled list Aug. 8, wavered. Some teammates noticed the change. Others said they couldn’t see a difference. Williams noticed trouble in Strasburg’s follow-through. Despite the trouble, he did not walk a batter, but the discomfort — caused by a knot he said acts up sometimes, similar to the trouble he had early this season — forced him from the game.

“I’ve just got some little ball that’s in the back there, can’t figure out what it is. Sometimes it gets upset and tried to battle through it,” Strasburg said. “Offense came through today and picked me up.”

Denard Span will not return this season. Michael A. Taylor will play center field, and Werth will lead off as the Nationals push for the playoffs.

Werth swung the Nationals back from what was a three-run first-inning deficit. After lining deep to left in his first at-bat against Marlins left-hander Brad Hand, he lined farther in his second and hit a two-run homer into the visitor’s bullpen. That scored Taylor, who singled to lead off that inning.

Taylor started for the first time since Thursday when he bruised his right knee after colliding with the center field wall against the Padres. He singled to lead off the fifth inning, too. Werth doubled him home. Werth finished with two hits and three RBI, and Taylor finished 2 for 4 with one crucial catch made barreling toward that wall in the sixth.

“Everyone’s working at-bats right now, trying to put the ball in play,” Taylor said. “I think we’ve been good with runners in scoring position, and we’re putting up runs right now.”

Starter-turned-reliever Doug Fister pitched two scoreless innings in relief of Strasburg, an unexpected long-relief man thrust into unexpected Sunday work. Felipe Rivero, the left-handed rookie called up from Class AA Harrisburg months ago and an integral part of the bullpen since, pitched another. Drew Storen and Jonathan Papelbon worked scoreless innings, too. Strasburg left injured, but the Marlins never scored again.

“You see the fire in the dugout. You see the fire in the stands. That’s what you want,” Fister said.

“That’s what September’s all about. We’re going to come up fighting.”

Ian Desmond walked three times, as many times as he did in June. Anthony Rendon went 2 for 5 and is 13 for his last 32 over an eight-game hitting streak.

Despite their injuries, thanks in part to a coalescing offense that has had to redefine “full strength,” the Nationals head to face the Cardinals, the best team in baseball, having won four straight series.

Since the start of that stretch of eight wins in 12 games, they fell a game further behind New York in the NL East.