Stephen Strasburg will take the ball for Game 1. (Jonathan Newton/The Washington Post)

Dusty Baker called Stephen Strasburg into his office at Nationals Park on Thursday morning. The Washington Nationals manager had some news for his all-star right-hander: He was starting Game 1 of the National League Division Series against the Chicago Cubs on Friday night.

Strasburg figured he would. A tight right hamstring has kept Max Scherzer off a mound since Saturday, and Strasburg was told to throw a bullpen session Tuesday. He was the other logical choice to pitch the playoff opener. But Baker still expected the confirmation to lure some emotion from Strasburg. Maybe a fist pump or a smile acknowledging he had drawn the prestigious assignment opposite the defending World Series champions. He got nothing.

“He had the same look when he left my office as when he came in,” Baker said, laughing, to roomful of local and national reporters Thursday. “It’s the truth, I swear.”

Baker’s attempt to convince the masses wasn’t necessary. Strasburg doesn’t let his guard down often, not even around his manager and especially not when he has work to do. And he had work to do Thursday in preparation for his second career postseason start in eight under-the-microscope seasons.

“He’s a perfectionist,” Nationals pitching coach Mike Maddux said.

To endure the regular season, that dogged desire for perfection had to be tempered. Strasburg was reminded that quest was futile last September when he walked off the mound with a partially torn pronator tendon, leaving him to watch the Nationals compete in the postseason without him for the second time in five years months after signing a $175 million contract extension. All he had on his postseason résumé was a Game 1 start against the San Francisco Giants in the NLDS in 2014. He allowed two runs in five innings in a loss.

“From Day One, there was pretty high expectations,” said Strasburg, 29. “You know, I think you just have to do a little bit of soul searching, look yourself in the mirror. And when things don’t go well, learn from it.”

Strasburg was baseball’s most dominant pitcher down the stretch. (Alex Brandon/AP)

Strasburg’s lesson produced changes designed to ensure postseason availability and resulted in the best season of his career. The right-hander ranked fourth in baseball in ERA (2.52) and fifth in WHIP (1.015). He allowed the fewest home runs per nine innings (0.7) in the majors and had the lowest FIP (2.72) in the National League. Most importantly, he logged 175 1/3 innings across 28 starts and didn’t break down.

“He’s like your silent assassin,” Scherzer said. “He goes out there and knows what he wants to do and executes pitches. He has nasty stuff and can match anybody pitch for pitch. He’s truly one of the best arms in the game right now. He’s fun to watch.”

Strasburg’s start-to-start preparation changed this season. Last season, he threw two bullpen sessions in the four days between outings. He would throw around 30 pitches in one and around 20 in the other. He wanted everything to be same every time and wouldn’t step off the mound until he was satisfied. He jumped out to a strong start in 2016, but landed on the disabled list twice in the second half. This season, Strasburg threw one bullpen between outings. He kept each session between 25 and 30 pitches. He was consistent. His craving for perfection was curbed.

“He stayed within his little area there,” Maddux said. “He’s been pretty good at it. He has his routine. Execute a couple this side, a couple that side. Throws each pitch in a sequence like he works a hitter and calls it a day. And if he misses that last pitch he’ll throw another one. And if he misses that one, he’ll have the discipline, ‘Okay, I’m going to make it now and I’m done.’ He’s had a very good work ethic. All the preparation and commitment are there — just not the volume of throwing.”

The second change was mechanical: ditching the windup to pitch exclusively from the stretch. He made the decision on his own last winter after watching video of others having success with the unorthodox approach. His goal was to simplify his mechanics. Simplification means repetition. Repetition of good mechanics means less stress on his body. Less stress means fewer missed starts. Maddux said he didn’t realize Strasburg was abandoning the windup until he pitched in his first intersquad game in spring training. He didn’t flinch.

“I was all for it,” Maddux said. “The biggest pitches you make over the course of a game are out of the stretch. So let’s feel very, very comfortable in the stretch and confident in the stretch. And you have more options in the stretch. Holding the ball. You can slide step. Quick pitch. You just have more options.”

The switch hasn’t impacted Strasburg’s ability to get batters out. Last season, Strasburg faced 364 batters with the bases empty, when a pitcher uses the windup. They batted .209 with a .619 on-base-plus-slugging percentage, 33 walks and 116 strikeouts. This season, 427 batters hit .217 with a .597 OPS, 25 walks and 131 strikeouts with the bases empty.

The final major alteration was pitch selection. Last season, Strasburg threw a slider 17.1 percent of the time, according to FanGraphs. That mark was, by far, a career high and Strasburg attributed his pronator tendon tear to the dependence. He vowed to throw it less, and he did. This season, 6.1 percent of Strasburg’s 2,742 pitches were sliders. Maddux said the usage depends on the matchup. If the slider is considered a better alternative than his curveball against a certain team, he’ll throw the slider more often. But if the difference is negligible, he’ll opt for the less stress-inducing curveball.

“My ultimate goal was to be there at the end,” Strasburg said. “And I was able to accomplish that … I just look back on that as a learning experience in itself. And to not necessarily go out there and think like small picture, like next start, but big picture.”

Discomfort in Strasburg’s reconstructed right elbow surfaced in late July anyway. He said he probably would have tried to pitch through the ache in the past. Instead, he went on the disabled list for 23 days and emerged on Aug. 19 to pitch to an 0.84 ERA in 53 2/3 innings over his final eight starts of the regular season. He was the best pitcher in baseball during the stretch, good enough to catapult himself into the National League Cy Young race and start Game 1 even if Scherzer were healthy.

“He’s just really showing his true colors, man,” Maddux said. “He is a warrior. He’s a fighter. He’ll take you down to the last pitch, whatever it takes.”

Strasburg will have the opportunity to fight in a playoff game Friday. It’ll be a rare sight, one the baseball universe expected more frequently when Strasburg opened this ongoing chapter in Nationals history with an electrifying debut in 2010 that only escalated sky-high expectations. They remain visible all these years later in the press box area high above Nationals Park, where several framed magazine covers hang on walls. On one, a 2013 season preview, Strasburg is following through on a pitch in full uniform. He’s staring straight ahead, his left leg planted and his right leg in the air. Between them: “Mr. October.”

“This isn’t pressure,” Strasburg said. “This is a game.”

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