HOUSTON — Over the winter, Jordan Montgomery spent his days at Tread Athletics, a performance lab about 10 miles outside of Charlotte, fine-tuning his pitching craft. While the coaches at Tread appreciated almost everything about Montgomery, from his size to his competitiveness to his willingness to learn, what they loved most of all was his curveball. They loved it so much that it earned a nickname:

The Death Ball.

To the naked eye, it looks like a perfectly OK curveball, and based on spin rate and break alone, it’s nothing special. And it confounds hitters anyway.

Yordan Álvarez learned its power first-hand Sunday night in Game 1 of the American League Championship Series. The Houston Astros slugger, one of the best hitters in the world, coming off a division series in which he hit four home runs in four games, faced Montgomery three times. All three ended with Álvarez swinging through the Death Ball. Never had one pitcher struck out Álvarez three times in a single game.

Montgomery isn’t just any pitcher. Acquired by the Texas Rangers at the trade deadline for exactly a night like tonight, the 30-year-old authored one of the best — and certainly the most important — starts of his career in Game 1. He threw 6⅓ scoreless innings and neutralized Álvarez in the Rangers’ 2-0 victory that pilfered home-field advantage from Houston and silenced the once-raucous crowd of 42,872 at Minute Maid Park.

In the three at-bats Montgomery squared off with Álvarez, he threw 17 pitches — eight sinkers, six Death Balls, two four-seam fastballs and even a changeup, a rarity for a left-handed pitcher against a left-handed hitter. He worked inside and outside, up and down, completely avoiding the middle of the strike zone. If a pitcher is going to beat Álvarez, he needs to empty his bag of tricks.

It’s a good thing Montgomery’s curveball is magic.

“When it comes out of his hand, it looks like a fastball,” Álvarez said. “That makes it a little more difficult. The way he releases the ball, the angle he releases it, makes it a little bit more difficult to pick it up and makes it look like a fastball.”

This is why, even with the analytics that inform so much of baseball today, context matters. At Tread, Montgomery worked not only on the shape of his pitches but how his delivery presents them. Álvarez suggesting Montgomery’s curveball looks like a fastball might sound outlandish — the average velo on Montgomery’s fastball Sunday night was 93.3 mph; on the curveball, 79.8 — but he’s not wrong. It’s how Montgomery and his coaches designed it.

They recognized that Montgomery had two things working in his favor on the pitch: his height and his release point. It didn’t spin particularly hard, and it didn’t have the looping action a more aesthetically pleasing curve might. It came out flat and broke late — and when paired with this sinker and four-seam fastball, it turned into the reaper.

Montgomery’s release point on the Death Ball is 80.2 inches from the ground, the second-highest vertical release on a curve in baseball (behind his opponent in Game 1, Justin Verlander). Montgomery releases his four-seamer 80.4 inches vertically and his sinker 80.9 inches — and the horizontal release point on all three are within a half-inch of one another. The tunneling effect charms hitters into believing they’re seeing one thing when it’s something else, and it’s what left Álvarez flailing, with five whiffs among the 17 pitches he saw.

When he was around 12 and growing up in South Carolina, Montgomery learned to throw a curve when his father, Jim, helped him wrap duct tape around Coke cans to give them extra weight. Montgomery would try to spin them into a nearby garbage can. Eventually he got the feel for the pitch, rode it to the University of South Carolina and used it to get to the major leagues with the New York Yankees. They traded him to the St. Louis Cardinals last season, and the Cardinals received a bounty from the Rangers in the late-July deal that landed him in Texas.

Upon his arrival, Montgomery didn’t think he’d be the team’s postseason ace, not with the subsequent acquisition of Max Scherzer, plus Nathan Eovaldi pitching like a frontline starter. But Eovaldi got hurt. And Scherzer did, too. And Montgomery found himself not only starting Game 1 of Texas’ wild-card series against Tampa Bay but doing the same against the Astros, whose seventh consecutive ALCS appearance extended the league record.

Álvarez helped carry the Astros here. The 26-year-old is a dream hitter: powerful but precise. He destroys right-handed pitchers — and crushes lefties, too. His holes are more pin pricks than swiss cheese. Carving him up takes the exactitude of a surgeon.

Dr. Montgomery started in the first with a clear plan: Work Álvarez inside. He started with a low-and-inside sinker that Álvarez fouled off, moved up and in with a sinker Álvarez took for a ball and then pounded three more pitches inside: a curveball Álvarez took for a strike, a sinker he fouled off and a curveball he swung through.

“We know he likes to get extended, and we were going to make him beat us inside, make him a little uncomfortable,” said Rangers catcher Jonah Heim, an All-Star who is widely lauded for his game-calling and framing abilities. “And when he’s kind of squirmy, we try to get him, and the curveball plays. [Montgomery] did an amazing job of execution.”

The second at-bat might’ve been even more impressive. In all the years Montgomery spent in the AL East, he learned that the best hitters, like Rafael Devers, will eventually sell out on an inside pitch if you keep pounding there. So after missing low and in with a sinker, Montgomery feathered a middle-away four-seamer through which Álvarez swung. He came back high and in with a sinker Álvarez fouled off, tried to change his eye level with an even higher four-seamer and went inside again twice — a changeup for a ball, a sinker fouled — before another Death Ball.

“I wanted to make him swing,” Montgomery said. “I was going to make him beat me with my best pitch there. And usually when you don’t miss middle, it’s a good day.”

That’s the thing about Montgomery. He’s not a nibbler. He’s not someone who picks at the corners. He goes right at hitters. And he isn’t afraid to go deep into his repertoire. Earlier this week, Rangers outfielder Robbie Grossman was telling Montgomery that he needed to use a slide step to the plate rather than his full delivery when nobody was on base. Well, in his third at-bat against Álvarez, down in the count 2-0, Montgomery conjured one more trick and froze Álvarez on perhaps the most hittable pitch he’d see all day, a sinker low and across the middle of the plate.

“It’s not only the curveball,” Astros third baseman Alex Bregman said. “He’s got a bunch of other weapons as well, and he executes really well. So I think it’s just execution really. It’s a good pitch.”

Montgomery knows that, and so after getting that first strike against Álvarez, he wasn’t throwing anything else. On 2-1, Montgomery threw a curve toward the bottom of the strike zone; Álvarez swung over it. The next pitch was a bouncer, nowhere close to the plate, and it left Álvarez flailing, looking less like one of the best hitters in the world than a guy who was utterly perplexed by what he was seeing.

Three at-bats. Three strikeouts swinging to end the inning. And one gift of a performance, to both the Rangers and his family.

On Saturday, Montgomery’s wife, McKenzie, celebrated her birthday. And on Sunday, it was his father’s, and Jim had been asking for a playoff win as the perfect present. An ALCS win against a future Hall of Famer sufficed.

Montgomery isn’t done. He’ll likely start another game this series, when he’ll line up against Verlander again. He’ll go through the meticulous pregame routine of plyoball drills that his coach, Tyler Zombro, taught him at Tread — the ones that help him find consistency in his delivery and conviction in his movement. He’ll get together with Heim and his pitching coach, Mike Maddux, with whom he vibed almost immediately after arriving, and he’ll game plan.

And then he’ll try to keep doing exactly what he has done all postseason and what he hopes to do all the way through the World Series: spin ’em to death.