Jayson Werth celebrates with teammates as he heads back to the dugout after hitting the second of his two home runs Wednesday night. (Matt Slocum/Associated Press)

This Washington Nationals season carried emotion with expectations, poignancy that comes in part from a sense of finality. Many of the players that grew into stars as the Nationals built themselves into a contender will most likely be gone next season. Clubhouse constant Ian Desmond, sparkplug Denard Span, reliable Jordan Zimmermann and others seem certain to depart. The roster will look different next year. This group, as constructed, wanted to win together. They still can, though the odds are long.

But for all the changes coming, the Nationals will hardly transform. The players who keyed their 12-2 win over the Philadelphia Phillies on Wednesday night will all be back. That win clinched a three-game sweep and extended a four-game win streak, propelled in large part by four home runs in three nights by left fielder Jayson Werth, including two Wednesday.

Werth, a veteran as crucial to the Nationals team dynamic as anyone, is not going anywhere. Neither is Bryce Harper, who hit his 40th home run of the season. The Mets lost, 6-0, to Miami in New York, so the Nationals’ deficit in the East is 71/2 games with 17 remaining.

Werth and Jonathan Papelbon are the only Nationals who have played in a World Series. Werth did that with the Phillies in 2008 and 2009. Werth has played 74 of the Nationals’ 145 games and arrived in Philadelphia with seven home runs in 2015. He hit two, including a grand slam, in Monday night’s win. Wednesday, he added solo homers in the fourth and the sixth.

Matt Williams won NL Manager of the Year in 2014, but the Nationals fell short of playoff expectations last season and have underperformed this year. Is Williams in danger of losing his job if the team misses the postseason? (Post Sports Live/The Washington Post)

“It’s very special to see him come into Philly and do that,” said Harper, who bolstered his MVP candidacy with his third home run in the past two games. “Love seeing him do that here, especially because they boo him and things like that. It’s fun to see. He’s unbelievable inside the clubhouse, unbelievable out on the field, and he brings a lot to the table.”

Werth scored the Nationals’ first run when he walked in the second and then came home after two Phillies misplays moved runners around the bases. The Nationals also got two runs in the fifth inning when Jose Lobaton and Michael A. Taylor singled and Gio Gonzalez bunted them to second and third with one out. Anthony Rendon singled, and Lobaton scored before Taylor was caught between third and home. Then Yunel Escobar doubled home Rendon. Harper singled to center, and Escobar was called out at the plate.

Replays showed he may have been safe. Though the Nationals challenged, the call was not reversed. Escobar left the game in the eighth inning with a tight hamstring aggravated on the slide. The Nationals scored three runs on two hits in that inning.

Four players under team control next season — Rendon, Escobar, Harper and Werth — drove in two runs each in the game. Rendon and Werth scored three runs apiece, too.

“[Werth] plays hard, plays like he’s having fun. He brings it to the clubhouse and the dugout,” Gonzalez said. “Just keeping it nice and loose when we need him.”

Asked about Werth, Harper called him “one of his best friends,” a brother, and said he was glad to have him hitting behind him. Harper hit two home runs Tuesday night and added a two-run shot in the top of the seventh Wednesday, his 40th home run of what could be an MVP season. Only six other players have hit 40 home runs in a season at age 22 or younger. Four are all in the Hall of Fame and the others won multiple MVP awards. Harper is not going anywhere either.

“He’s become a superstar player right in front of our eyes. I think he’s got a lot to learn and a long way to go,” Werth said. “I’ve said before, when he’s 30 years old he’s going to be a hell of a player.”

Gonzalez was acquired before the 2012 season and has also been a part of this Nationals rotation as long as it has carried playoff expectations. He is one of two starters, along with Zimmermann, to make every start this season, though he has been inconsistent at times. He will likely be the lefty in the Nationals’ rotation through the end of his contract in 2017.

Wednesday night, he pitched seven innings and struck out 12, which tied his career high. He has struck out at least 10 in two of his past three starts. He walked two and was relatively efficient given that high strikeout count: He threw 110 pitches, 78 of them strikes, showing again what happens when he attacks instead of nibbling.

For all the reminders Wednesday night’s win provided about the constants for the future, it also kept hope alive for their present. The Mets’ loss to the Marlins narrowed the gap, even as time runs short. Werth was on the Phillies in 2007 when they trailed the Mets by seven games with 17 to play. They won the division.

“Everybody knows,” Werth said. “Everybody’s aware. We gotta believe, and a lot has to happen.”