HOUSTON — Atlanta’s most indispensable reliever this postseason was so dispensable three years ago that he could not even find a job in baseball. So he bought a Facebook advertisement and landed with an independent league team in Texas.

He lived in an R.V. that summer, in 2018, and cashed a paycheck of around $400 every two weeks, with no idea whether he would win or go bust.

The story of Tyler Matzek’s rise from the Texas AirHogs to the World Series features international relations, a former member of the Navy SEALs and security guards. Now, it also includes appearances nearly every night on the October stage with the Braves. When the stocky, 6-foot-3 left-hander entered Game 1 of the World Series here Tuesday night, it was his 10th relief appearance in Atlanta’s 11 postseason games.

His biggest outing came in the decisive Game 6 of the National League Championship Series. He earned the win in part by striking out Albert Pujols, Steven Souza Jr. and Mookie Betts in succession. He had entered the game with Atlanta clinging to a 4-2 lead over Los Angeles in the seventh inning. Runners were on second and third with no outs, but he left them stranded.

“The perseverance is something I’ve never seen in 52 years in baseball,” said John McLaren, the former Seattle Mariners manager who coached in seven major league organizations, scouted for another and was the skipper who welcomed Matzek to the AirHogs in 2018.

“You really can’t appreciate the situation unless you know where he was,” McLaren said.

The Colorado Rockies picked Matzek in the first round — 11th overall — in the 2009 draft out of Capistrano Valley High School in Orange County, Calif. He ascended through the Rockies system, made 20 appearances (19 starts) in 2014, his first season, and started their home opener in 2015. But in just five starts in 2015, he walked 19 batters in 22 innings and was sent down to the minors.

He had been stricken with a case of the “yips,” where an athlete becomes unusually nervous or tense during a crucial action of the sport. In his case, it was a sudden and unexplainable loss of ability to throw strikes.

Matzek never again pitched for the Rockies. He languished in the minors for the rest of 2015 and all of 2016. He went to spring training with the Chicago White Sox in 2017 but was released in late March.

“It took time,” Matzek said. “It was changing my mind-set. I always tell people we have fear in our lives and we have three options: Flight, fight or freeze. The yips is, you choose to freeze. You put all that fear into freeze and your body just stops working when you throw the ball. You can’t flight — you’re thrown into the game and you’re going to pitch.”

So while sitting out 2017, he chose “fight.” Through a connection with Michael McKenry, Matzek’s friend and former catcher with the Rockies, he enlisted the help of Jason Kuhn, a former member of the Navy SEALs whose own career as a pitcher was cut short by a case of the yips while at Middle Tennessee State. Kuhn now runs a company called Stonewall Solutions in Nashville that travels to high schools and colleges planning training programs for sports teams.

“Yips isn’t something you think away,” Kuhn said. “You’ve got to go train it away.”

Kuhn likens it to “pulling a hamstring in your brain.” The pair worked together for a time in Nashville, then continued the work over the phone and with worksheets that gave Matzek questions to answer pertaining to fundamentals that focused on things like mental toughness and a team-first mind-set.

“It was all mental,” Matzek, 31, said. “I was nowhere even near the strike zone. There was a point where I was playing catch with a guy, I’d have him stand by the fence and throw the ball at him, or try to throw it at him, and I’d miss by 15, 20, 30 feet. The ball would hit the ground, he’d grab it and toss it back to me.

“I just figured the more times I throw it wrong, I’m closer to throwing it right. So I just kept going.”

In the winter of 2017-18, his work with Kuhn continuing, Matzek said, he paid some $3,000 to play in an independent tryout league based in Palm Springs, Calif.

“I kid you not, we had guys that had never played baseball before in that league,” Matzek said. “We had football players who were trying to play baseball for the first time in their lives and anything and everything in between. Some guys were security guards in their regular life and just wanted to come out and try out.

“I paid three grand for that for a month just trying to get back to playing ball.”

The Mariners saw him, signed him, but then released him at the end of spring training.

Andy McKay was Seattle’s director of player development and had a history with Matzek in Colorado’s organization. A part of McKay’s background is as a mental skills coach. He told Matzek that the Mariners had no place for him in the minors, but that they would keep him in extended spring training if the pitcher wanted. He encouraged Matzek to play independent ball instead, however, because Matzek needed to pitch competitively and in front of fans, not on deserted back fields.

So Matzek took out the Facebook ad — “I did it myself,” he said, meaning he did not have an agent involved. That ad led to a season-long commitment from Billy Martin Jr., the general manager of the AirHogs. Matzek borrowed the R.V. from McKenry and drove from Nashville to Texas.

“It was brand-new, maybe two or three years old,” Matzek said of the vehicle. “It had great air-conditioning, honestly. Just kept the blinds down all the time. It gets hot out there, 120, 130 during the day.”

The AirHogs had signed a partnership deal with China’s national team, which “sent over 30, 40 guys to learn U.S. baseball to get prepared for the Olympics,” Matzek said. The situation created a language barrier but ultimately led to friendships.

McLaren said that Matzek’s situation was “demons, birdies on his shoulder talking to him, true grit and hard work.” He continued: “It was great for the Chinese players to be around him. He rooted for his teammates, was aggressive, checked every box there was as far as having physical talent but still being rock bottom.”

Matzek said: “There were times I was throwing the ball 85, 86 miles an hour, just lobbing the ball in there, trying to throw strikes. And it was not pretty. Not good.”

But it got better. Eventually, Dana Brown, Atlanta’s vice president for scouting, pestered General Manager Alex Anthopoulos toward the end of the 2019 season to sign him. Now, Anthopoulos said, he forwards Brown that original email each year around the time Atlanta signed Matzek because: “I can’t thank Dana enough. If he doesn’t pound for him and send scouts to see him, he isn’t here.”

This is why, when Matzek fanned Betts to extinguish the Dodgers’ final threat on Saturday night in Georgia, so many people were so happy.

“Absolutely incredible,” said Atlanta’s Freddie Freeman, who was Matzek’s first strikeout victim in the majors back in 2015.

At home in Phoenix, McLaren was watching while in touch with some of his former players from China, receiving texts and emails that read along the lines of “Tyler was great!” and “Three strikeouts in one inning, boy, that’s tremendous.”

“They’re on the computer no matter what time the game is, they’re following him over there,” McLaren said.

And in Nashville, Kuhn said he was watching with tears in his eyes.

“It was just fulfilling beyond measure to see him rewarded and succeed,” Kuhn said. “I told him when we met, you’re at a crossroads in life. Regardless of what you choose to do, you want to look back on this moment and be proud of who you are and what you choose.”

Sometimes the longest journeys can be the most rewarding. One day, a pitcher is an AirHog. Another, he is facing Betts with the World Series on the line.

“I know,” Matzek said. “Crazy, right?”