On Monday night, 3,000 fans stood in drizzle on the Southwest Waterfront to get into the first showing of Major League Baseball’s annual documentary on its latest World Series winner — this time, the Washington Nationals. When people will pay $35 to watch highlights of games they already have seen in their entirety, you have a hot product.

But how do you keep it that way? And build on it?

There were cheers, laughs and even gasps at key Nats home runs in October, as if the results were still a shock in hindsight. But there were also yells of “Sign Strasburg” and “Sign Rendon” aimed at principal owner Mark Lerner and General Manager Mike Rizzo onstage. Those loud outbursts seemed to be equal parts an entreaty and a blunt order.

If you think last season was riveting and a constant illumination of people’s characters, then this offseason won’t be far behind.

The Nats know they can’t define the life choices of others. On Monday, Rizzo said there had been no recent meetings with either Anthony Rendon or Stephen Strasburg but added, “We’ve been talking to them for 10 years.” Meaning: They know all about us, including how much we value them. But we can’t control them, only ourselves.

“We really can only afford to have one of those two guys,” Lerner told Donald Dell of NBC Sports Washington in an interview, part of which was posted on the outlet’s website Thursday evening. “They’re huge numbers. We already have a really large payroll to begin with. So we’re pursuing them, we’re pursuing other free agents in case they decide to go elsewhere.”

So what can the Nats control, especially in an offseason when agent Scott Boras, who usually draws out the free agency process into January or February to milk the last drop of leverage, represents the winter’s top prize, pitcher Gerrit Cole, as well as both Rendon and Strasburg?

The Nats need to focus on three areas while looking for their chance to re-up either Strasburg or Rendon.

They need to pursue a long-term market-value contract extension with Rizzo, who has been the Nats’ architect and central personality for the past dozen years. This should be obvious because Rizzo is in his lame-duck walk year in 2020. But is it obvious to the Lerners?

On Tuesday, Rizzo was chosen executive of the year by Baseball America. His résumé is now top-shelf. Which means, in baseball’s goofy world, you can still get him for roughly the annual salary of part-time catcher Yan Gomes. You want a “market inefficiency” to exploit? Try “GM salaries for $100, Alex.” Why does this even require thought?

Rizzo might even be the GM whom Boras respects the most — because Boras thinks a key to his success is that, as an ex-player, he has a scout’s eye. The scout’s scout? Rizzo.

Many Nats believe, especially after this past season, that Rizzo could fix the hull of the Titanic with a toothpick. He signed Kurt Suzuki and Gomes as a new catching duo, when neither was in high demand. They combined for 29 homers and 106 RBI. He assembled platoons at first and second base out of driftwood; they produced 37 homers and 128 RBI and 30 homers with 96 RBI, respectively. He built a bullpen that stunk. Then he saved it at the trade deadline with Daniel Hudson and a playoff plan to have his aces help out in the bullpen. He got Gerardo Parra and Asdrúbal Cabrera free — ex-teams paid ’em.

Next on the agenda is preserving the team’s culture. The Nats did not just win a World Series last season; they redefined their clubhouse. That was a conscious Rizzo/Lerner project. Now they need to reassemble as much of that fun-loving, team-first, low-cost, hard-nosed, aged bunch as possible.

No one at Nationals Park will say that subtracting Bryce Harper was needed to improve chemistry, increase accountability, banish baseball’s typical big-ego star system and make room for who-knows-what — maybe even a Baby Shark — to bloom. But it was a key. Everyone knows it, and the lesson only is reinforced by Harper having a typically productive slugging season in Philadelphia yet the Phillies finishing .500 and firing their manager.

The Nats can’t just round up every 2019 “glue personality” who’s now free on the street and say, “How much do you want?” But they need to give extra intangible weight to the value of Howie Kendrick, Ryan Zimmerman, the versatile Cabrera, Brian Dozier, Matt Adams and the modest but must-re-sign Hudson.

You won’t keep them all. Rendon may come back. For sure, rookie Carter Kieboom will be asked to take over an infield spot. But keep as many of the men who experienced the grit and magic of 2019 as possible. Team cultures can last decades. From 1960 through 1985, Baltimore won the most games in the majors with modest budgets by preaching the Oriole Way. Now every team in every sport brags about its “Way.” The O’s really had one — with pitching, fundamentals, defense and brains.

The Nats are now eight seasons into such a tradition. They can’t let it slip. Some years will stink. After the O’s won their first World Series in 1966, they went 76-85 the next year. But their methods stayed intact. And they won 409 games the following four years with three pennants.

Finally, as the Nats cope with their options in a market in which they may lose Rendon or Strasburg, they can’t overlook the chance to grab a star — and close a door on a popular hero — if that player perfectly mirrors the current D.C. culture. Third baseman Josh Donaldson, 33, a former AL MVP with a .900 on-base-plus-slugging percentage last season, fits that definition and may cost $75 million for three years. He’s not Rendon, but he’s the right personality type if Anthony seems to be drifting away.

Among free agent starting pitchers, Madison Bumgarner has a champion’s pedigree and temperament.

Also, the Nats tend to think bigger and bolder than those of us who analyze them. Nobody spotted Jayson Werth, Max Scherzer or Patrick Corbin as new Nats. If the Nats conclude both Strasburg and Rendon will leave, would Cole, a better bullpen and Kieboom at third do just as well?

Baseball games are fluid, constantly changing before our eyes. But as these mind-bending permutations show, so are winter negotiations. Last year, the Nats struck more quickly and often than any team. By signing Corbin, the top target, at this time last December, they effectively (and soon publicly) said so long to Harper.

This offseason, the Nats seem committed to keeping their door open longer to give one of their home-grown products, either Strasburg and Rendon, every chance to stay. But now it’s clear: not both. There’s complexity everywhere, including the motivation for one of them to take the Nats’ money while it’s still available.

What cannot and need not be lost is the culture that this Finish the Fight team brought to life. Rosters change. Lucky and luckless seasons both arrive. But once a team sees what values it wants to embody — and what kind of players and people make that possible — then that’s the lodestar to follow.

For more by Thomas Boswell, visit washingtonpost.com/boswell.