Sean Doolittle and the Washington Nationals players toss souvenirs to fans who stuck around Nationals Park after Sunday’s game to watch Braves-Marlins after they clinched the NL East title Sunday. (Katherine Frey/The Washington Post)

The first man out of the tunnel was Stephen Strasburg, whose eight scoreless innings helped the Washington Nationals win, 3-2, on Sunday, then sent them back down that tunnel to the most positive sort of purgatory. Strasburg led the way when his teammates marched back out, wearing National League East champions T-shirts and goggles, greeting the few thousand fans who stayed to watch the Braves beat the Marlins nearly 90 minutes after the Nationals’ game ended.

Perhaps it was fitting that Strasburg, the draft pick who started this remarkable franchise turnaround, was the man pitching on the day the Nationals won back-to-back division titles for the first time in team history.

That unpleasant one-year-on, one-year-off pattern no longer can be held against their résumé. They have won four of the past six NL East titles and were the first team to clinch a division this season. These Nationals are one of the more dominant teams of the decade.

Core members such as Jayson Werth and Bryce Harper were among the first to follow Strasburg onto the field, where they tossed hats to fans and greeted their families. The whole thing was rather subdued, as these things go. After all, the Nationals expected to win this division all along.

Still, division titles are never a given. Each year brings its own kind of chaos, its own tests, its own angst. As Werth walked up the dugout steps, he paused to hug Ted and Annette Lerner, then stooped to give an even longer hug to their son Mark Lerner, who lost a leg to cancer this season.

So much can change in six months of a baseball season, and often so much does. No moment like Sunday’s should be considered inevitable. No celebration, however routine it has become for this team, should be taken for granted. For the Lerners, Werth and so many others, this win will not be.

“It is not easy to win baseball games at the major league level. It is not easy to win division championships,” said General Manager Mike Rizzo, holding two beer bottles and apparently drenched in the contents of a few others.

“To look at the amount of games that we’ve won, the amount of days we’ve been in first place, the amount of divisions that we’ve won, it’s really mind-boggling to think about.”

Harper, for example, knows nothing but winning during his Nationals tenure. When he reached the top step of the dugout, he turned and clapped his hands over his head to acknowledge the fans, showing hardly any of the unfiltered emotion that has defined him for the past half decade. He has not been able to play for several weeks.

Harper, like so many other key Nationals, has missed a significant amount of time because of injury this season. But the Nationals (88-55) never sputtered, never lost more than four games in a row and spent only three days out of first place.

Fittingly, it was a lineup of all youngsters, which included no regular starters beside Trea Turner, that won the last game the Nationals needed Sunday afternoon. So many of them — such as Adrian Sanchez, who doubled home Turner in the fifth, or Victor Robles, who doubled home Sanchez in the same inning — never would have gotten a shot this season if it weren’t for all the nicks and bruises. But because they seized their opportunities, the Nationals did not succumb to injuries like they did when they were favorites in 2015.

“It tells us that the depth we’ve created in the organization is second-to-none,” Rizzo said. “. . . I call [Manager Dusty Baker] the magician because he’s put together some lineups that look kind of crazy at times, but the proof’s in the pudding. All he does is win.”

Baker sat in his office as the Marlins-Braves game wound to its later-than-expected conclusion, about to nod off when the game ran long. He has led seven teams to division titles and will appear in his ninth postseason as a manager in October. Only six managers have reached so many. All of them are in the Hall of Fame.

“I remember Pat Riley and John Wooden talking about how different [all years] are and the struggles of each one,” Baker said. “This year was very, very gratifying.”

Strasburg, whose eight scoreless innings ran his streak to 34, watched in the video room where he could track his NFL fantasy players in the Packers-Seahawks game. Some Nationals sat on couches in the clubhouse, where temporary beige carpet was duct-taped over the normally dark floor and plastic wrap perched above the lockers in case valuables needed protecting.

Gio Gonzalez, the clubhouse DJ, turned on the Braves tomahawk chop music as the innings went by. Matt Albers, who had never been a part of a division-winning team in a decade in the majors, switched chairs over and over, hoping superstition would help the cause. The clubhouse erupted when Lane Adams hit his walk-off homer. About a half-hour later, it was all drenched in celebration.

Rizzo took all of the wet chaos in, standing aside and addressing reporters as the celebration wound down, and his voice grew more serious.

“Look, I get it. We’re not satisfied,” he said. “We want to do more. We expect to do more.”

His Nationals ultimately will be judged on more since they have never been able to achieve it. But more comes later. On Sunday, after five months and 90 long minutes of waiting, the division title was enough. Winning it was, as they said, much harder than it looked.