HOUSTON — Take any of Sean Doolittle’s big moments this postseason — leaping off the mound after eliminating the Los Angeles Dodgers, clicking when the pressure builds, recording four outs to help the Washington Nationals win Game 1 of the World Series — and then take a step back.

Doolittle is here, revamped, reinserted in a closing role, because the Nationals took a calculated risk two summers ago. They needed someone to anchor their bullpen. They often have in their eight-year quest to right now. So they traded Jesús Luzardo in a three-player package to net Doolittle and Ryan Madson from the Oakland Athletics. This was just months after they sent pitchers Lucas Giolito, Reynaldo López and Dane Dunning to the Chicago White Sox for Adam Eaton.

Luzardo is still one of the league’s most promising young arms. Giolito should get a handful of American League Cy Young Award votes. That’s the cost of trying to contend every season. It takes a willingness to part with top prospects and a lot of money. The Nationals began the process in 2012 and are now two victories away from the ultimate reward.

“If Sean Doolittle is getting outs for us in the World Series, then giving up Luzardo was worth it,” a member of the Nationals’ front office said in March, sitting by a back field at their spring training facility in West Palm Beach, Fla., suggesting that organizational pitching depth can be defined in many ways. “If that happens, then you can look at that deal and say: ‘Okay, it really worked. It made sense.’ ”

And now here we are, in the final week of October, with the Nationals two wins away from their first World Series title.

“It’s difficult to win consistently and have a good farm system,” General Manager Mike Rizzo said before the Nationals beat the Astros, 12-3, in Game 2 on Wednesday. “Because you use your prospect capital to acquire major league players. But that’s been our plan the whole time.”

The bottom line — in the spring, in Houston this week, always — is pretty simple for the Nationals: A championship would make the deals worth it.

Maybe the long view of the Doolittle trade won’t look great for them. Blake Treinen and Sheldon Neuse were also shipped out alongside Luzardo. Parting with Giolito, a 25-year-old budding ace, is already favoring the White Sox. The Nationals entered this season a bottom-10 minor league system, according to multiple major ranking sites, and are hoping a few pitchers make sharp turnarounds. But the Nationals are close to having a sound, if not short-term, justification for their actions. There’s great risk in trying to build a contender every winter. And Rizzo, a longtime area scout, knows how hard it is to find talent that translates to the major league level.

Yet he is deliberate in using the Nationals’ scouting department as a real-time tool. Washington has a homegrown nucleus of Stephen Strasburg, Anthony Rendon, Ryan Zimmerman, Juan Soto and Victor Robles. They added Max Scherzer, Patrick Corbin, Kurt Suzuki and Aníbal Sánchez, among others on this team, in free agency across the last half decade. That leaves Trea Turner, Yan Gomes, Daniel Hudson, Eaton and Doolittle as the key pieces brought in via trade.

“A lot of them are on the field for us,” Rizzo said of the players his scouting department brings in. “But a lot of them turn into Trea Turner and Joe Ross. They turn into Sean Doolittle. They turn into those types of players. We’re always here to win now.”

The Nationals didn’t give up much for a 22-year-old Turner in 2015. The return for Gomes included outfielder Daniel Johnson, who made the Futures Game this summer, but Johnson is still in the Cleveland Indians’ system. Hudson cost a mid-level pitching prospect at the July trade deadline. Eaton and Doolittle were swapped for very notable players.

Eaton, 30, has four hits, a home run and three RBI in the World Series. Doolittle, 33, has reemerged as the most important pitcher in a thin bullpen.

“I feel like I’m doing what I was brought here to do and contribute meaningful innings in the back end of games for a winning team,” Doolittle said in Houston on Wednesday. “But watching Luzardo throw for Oakland this year, I joked to guys here several times like, ‘I can’t believe you traded that guy.’ ”

Doolittle admits to thinking about Luzardo and the trade when he first arrived in Washington in 2017. That Nationals team was playoff-bound and put him right into a high-leverage role. He excelled, posting a 2.40 ERA in 30 appearances, then made his second All-Star Game the next season. That made him feel like he returned the Nationals’ investment.

Then Luzardo was called up by the Athletics this September and flashed his dominant stuff, and just like that, Doolittle saw the 22-year-old all over clubhouse TVs. It mostly made him laugh and crack the same one-liners. They always will be linked, at least to some degree, and he’s more than at peace with that.

But the veteran was busy rebuilding his mechanics after spending two weeks on the injured list in late August. He had to rest his arm and deal with lingering issues in his right knee. It continued a year-long battle with his mechanics, starting in March, and Doolittle didn’t really solve them until a matchup with Kolten Wong in St. Louis on Sept. 16.

Wong was fouling off Doolittle’s fastball and the lefty needed a backup plan. So he tried a slide step — to throw off Wong, and to keep a base runner near first — and struck out Wong. He dove into the analytics after and noticed his spin rate and extension numbers were much better. He basically found a fix by accident.

He has been using a slide step ever since, for the first time in his career, and has allowed two earned runs in 8 ⅔ innings this postseason. He has finished three games. He is the only reliever remaining from the Nationals’ last playoff team in 2017. He’s one of just two relievers remaining from the bullpen they started this season with.

He is getting the biggest outs of a title run, like the front office imagined he could, but doesn’t tie that to how he got here. He will leave that to everyone else.

“I don’t like the idea of this team won a trade or that team did. I think it commodifies players in an unnecessary way,” Doolittle said. “Let’s just go win a World Series. How’s that?”

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