The Nationals won their final home game of the season against the Reds on Monday. Next year, the roster is expected to have many news faces and possibly a new manager. (Ricky Carioti/The Washington Post)

If Matt Williams had been at Ford’s Theatre in 1865, he would have loved the play. Did something go wrong? Nope, didn’t see a thing. Nobody said anything, either.

Next year, he and Jonathan Papelbon may be able to get together somewhere — not in Washington — and the reliever can tell him what a great brawl he missed.

The Washington Nationals knew their final home game of a dismal season would arrive Monday against Cincinnati. And they knew it would be a symbolic moment of change. A group of players, many of them friends for years, would be together as a unit for the last time. A team with the second-highest win total in baseball over the last four years would face a major transformation.

But now, in the aftermath of Papelbon starting a choke-and-brawl with Bryce Harper on Sunday in the Nats’ dugout, the need and the opportunity for radical change is greater than ever. Next year, a third of Monday’s Washington roster, if not more, could be gone, plus the manager.

And if the Nats are lucky, Papelbon will disappear, too. Somebody, somewhere must need an $11 million bouncer.

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)

Now it is not just Jordan Zimmermann, Ian Desmond, Denard Span, Doug Fister — all major stars for this team in ’14 but disappointments to different degrees this year — who will be leaving as free agents. Reliever Drew Storen, after an awful August that culminated in a broken thumb from smacking his locker, may want to be and need to be traded. Danny Espinosa could be so valuable as a regular shortstop in some other city that dealing him might be wise strategy, too.

For the Nats and their fans, this is a double-edged moment — and both edges are razor sharp.

On Monday, Max Scherzer, job description Ace for Eternity, did not give up a hit until there was one out in the eighth inning. Would he get his second no-hitter of ’15 and on the anniversary of Jordan Zimmermann’s in ’14?

“I was really rooting for a no-hitter today,” General Manager Mike Rizzo said sardonically after the game, a 5-1 win on a two-hitter with 10 Scherzer strikeouts.

Instead, Rizzo felt he had to say something that makes your head explode, like, “For the most part Papelbon has fit into the clubhouse culture fine.”

Presumably, the “other part” is trying to strangle a 22-year-old MVP.

Sometime in the next three years, Harper may decide whether he wants to sign a lifetime contract in Washington. Or, perhaps, look for a city where he never has been assaulted, then told he will have to sit out the next game — as the quintessential eyewash no-discipline-discipline — because he was “part of the incident.”

If Monday was damage-control-day, please let me be somewhere else when the Nats try to minimize a fight that actually draws blood.

The unfortunate permanent memory may be of Williams explaining how he could see the fight “out of the corner of my eye” but not think much of it and send Papelbon back out to pitch the ninth inning. Elephant in room, please call Matt.

Williams has gone from Captain Obvious in his news conferences to Captain Oblivious in his own dugout. Fine man, great career in baseball. Manager?

“I thought it was odd,” Rizzo said of Williams sending Papelbon back to the mound. “Matt missed it. He owned up to it. He said it was his fault. If he would’ve known, he wouldn’t have put him back in. . . . He made a mistake.”

And no coach or player felt close enough to Williams or concerned enough about him to say anything to keep the roof from falling on him? “Well, there’s plenty of mistakes to go around,” said Rizzo, who traded for Papelbon.

Now, as the Nats leave for a season-ending six-game trip, the rubble at Nationals Park can stop bouncing. And everyone can try to re-imagine the Nats’ future.

“Sometimes, shaking things up is what’s necessary. If every single person from this team came back, would I like our chances if we did it all again next year? Yes. But that’s not going to happen,” said Ryan Zimmerman, team patriarch.

“I wish I could play my whole career with Ian Desmond and Jordan Zimmermann,” Zimmerman added. “When I signed, I slept on Desi’s living room floor in Savannah” in the minors.

“Those two deserve whatever they get [in free agency]. Whoever ends up with them is going to be lucky,” Zimmerman said. “But some really, really good things are coming to this team. ‘Mix up’ could be positive.”

Zimmerman began the first big wave of homegrown Nationals talent, the cream of which — Desmond and Zimmermann — is now leaving.

“Here comes the second wave,” Jayson Werth said. “We’re going to find out what they’re made of.”

On Monday, the Nats’ lineup began with Michael A. Taylor, the center fielder who will replace Span, and Trea Turner, the shortstop who will eventually replace Desmond and be a natural No. 2 hitter. Joe Ross, who will take Fister’s spot in the rotation, and lefty Felipe Rivero, who touched 100 mph recently and looks like a setup man for ’16, were also on hand. There’s more behind them.

As a group, they’re the high-character type that Rizzo likes to brag about. He hasn’t been able to recently, thanks to Werth’s brief jail time for speeding and now Papel-gone’s high-character moments with Manny Machado and Harper.

As they cogitate this winter, the Nats need to remember that Zimmerman, Desmond and Zimmermann created an environment in which any player can conform to the group norm. And that norm produced 98-64, 86-76 and 96-66 records the last three years and an 80-76 record this year in the face of many injuries. Perhaps Harper is the perfect illustration of the reason the Nats need to go back to their basic values. Not to more Papelbons.

Papelbon’s pretext for yelling at Harper was that he didn’t run out a flyball hard enough in a 4-4 game, even though Harper did run to first base.

“Could Bryce have run harder? Yes, 100 percent for sure he could have,” Zimmerman said. “Could he have been on second [when the fly was caught]? Maybe.

“In this clubhouse, whether it’s [Stephen] Strasburg or Harper or any young player that’s come up, everybody is given a hard time when they mess up. And over the years, Harp’s gotten treated worse than anybody,” Zimmerman said.

“For years we wore him out, Werth and me and other veterans, whether it was in the clubhouse, on the bus. Back then, did he run ’em out and always play as hard as he should have? No.

“Does he run ’em out and hustle now — more than most [players] now? Yes. He does. And he’ll get even better than he is now.”

That’s the culture the Nats have had for years. What happened Sunday is the aberration that needs to be eradicated. The Nats are going through a major transformation. For it to be successful, they need to stick to the principles that have worked for them. Not look for new ones. Or put up with those, like Papelbon, who can’t live up to what — until recently — were known as the Nats’ high standards.