There was a time when Nestor Cortes was scared to be himself.

That reality is a bit hard to believe when it comes to a Yankees pitcher best known for the idiosyncrasies he brings to the mound. Cortes is a contortionist who thrives on disruption, an oddity among the creatures of habit that baseball breeds.

A Cuban southpaw who changes his delivery at will, Cortes uses a variety of arm angles, leg kicks, hesitation moves and quick pitches. His bag of tricks made him an entertaining watch before his numbers warranted attention, yet he attempted to go mainstream when the Yankees first gave him a major league opportunity in 2019.

“When he would get called up, he would be too afraid to do it in the big leagues,” catcher Kyle Higashioka, who first caught Cortes at Class AA Trenton in 2016, said of his teammate’s quirks. “I kept texting him like, ‘Dude, you gotta be yourself when you come here.’”

It didn’t take long for Cortes to heed Higashioka’s advice. Soon enough, Rob Friedman’s popular Twitter account, Pitching Ninja, began sharing Cortes’s frequent stunts alongside videos of some of baseball’s nastiest pitches. But Cortes didn’t consider his regular repertoire nasty at the time. He was right.

After being returned to the Yankees after a brief 2018 stint with the Baltimore Orioles as a Rule 5 draft pick, Cortes posted a 5.67 E.R.A. in 33 games with the Yankees in 2019. That off-season, he was traded to Seattle, where he allowed 13 earned runs in only seven and two-thirds innings.

It was clear that a return to the minors awaited Cortes in 2021. Walking away from baseball never occurred to him, though. He had seen too many talented players give up too soon. Instead, he took a minor league deal with the Yankees, the team that had drafted him in the 36th round in 2013 out of Hialeah (Fla.) High School.

“All it takes is one opportunity or one guy to get hurt,” Cortes, 27, said before a recent game at Yankee Stadium. “You don’t wish that upon anybody, but it’s the truth. That’s how the sport is played. You get the opportunity, you take it, you run with it, and you make the best of it.”

Getting His Chance

Cortes had put together a solid 15 innings at Class AAA Scranton/Wilkes-Barre in 2021 when the Yankees found themselves short-handed at the end of May. But a promotion to the major league club seemed inconsequential at the time.

He had been a Scranton Shuttle reliever in his first stint with the Yankees, and the team simply needed fresh arms. But after walking four in his first game back, Cortes found an unforeseen groove, first as a reliever, then as a short-inning starter, and then, eventually, as a member of the Yankees’ rotation. His final 12 appearances were starts, and he finished the 2021 season with a 2.90 E.R.A. and 103 strikeouts over 93 innings.

Cortes parlayed that performance into a rotation spot this spring, and he’s continued to mystify batters. He has a 1.15 E.R.A. over his first three starts of 2022, and he has racked up 25 strikeouts over 15 ⅔ innings while walking only three batters. Twelve of those strikeouts came on April 17, when Cortes held the Orioles scoreless — and threw an immaculate inning. He most recently fanned eight Cleveland Guardians while allowing two earned runs over six and a third innings on Saturday.

Cortes has become a cult hero of sorts — Yankees Manager Aaron Boone recently used the phrase “The Legend of Nestor” — as his success seemingly came out of nowhere. But the truth is that Cortes had to wait and struggle for years before he shined.

“I feel like I’ve got knocked down a bunch of times. I’ve gotten back up for the worst for the best,” said Cortes, who is expected to start against the Kansas City Royals on Friday in Missouri. “This time around, since last year, thankfully, everything’s been going well, and it’s much sweeter. It’s much sweeter to be here and to do it for a big league team.”

So what has changed? How has Cortes gone from the fringes of M.L.B. rosters to a pitcher who is only half-jokingly called an ace?

For one, the spin rate has improved on all of Cortes’s pitches over the last two years, per Baseball Savant. He also adopted a cutter, his favorite pitch this season, and no longer toys with a curveball. Cortes’s fastball has also gained about two miles per hour, though he’s still averaging only 90.5 miles per hour.

“I’m understanding my pitch package a little better,” Cortes said. “I know what to do to get righties and lefties out evenly, no matter who’s there in the box. I know what my strengths are and I’m going to attack them every time.”

There is no denying Cortes’s stuff has improved, but his deceptive tactics also aid an arsenal that pales in comparison to baseball’s star pitchers.

“The art of pitching is just disrupting hitters’ timing. You can do that in a lot of different ways,” said fellow starter Jameson Taillon, listing examples such as changing speeds, location, arm angles, pace and delivery. “He kind of takes all that into account.”

Reliever Clay Holmes added: “Hitters are so locked in on seeing pitches out of certain tunnels and angles. When he can change those up, it can be a big advantage.”

Cortes has seen that advantage play out repeatedly.

“Once he’s been able to let himself play his own game and do the things he does, like the funky timing and funky windup, he’s pitching up to his potential,” Higashioka said. “As soon as we were working together in ’18 and ’19 and I saw what he was capable of in Triple-A, I knew that he could do this. It was a matter of him being comfortable enough to be himself up here. I think he’s been doing that the last couple of years, and it’s really good to see.”

An Unexpected Athlete

At 5-foot-11 and 210 pounds, Cortes is not one of the Yankees’ “physical specimens,” as Holmes put it. Holmes said that there was an unassuming element to his locker mate, something Cortes acknowledged after awkwardly diving into first base to secure an out against the Guardians. “Under this body, there’s a guy that’s athletic,” he quipped.

“People don’t see the prototype of being 6-foot-5 and throwing 98,” Cortes added the next day. “So I feel like some people, it’s going to take longer than others to believe in me.”

There is no confusion over Cortes’s athleticism in the Yankees’ locker room, however. His teammates revere his machinations on the mound, and the skill required to effectively pull them off. Most pitchers — Holmes and Taillon included — wouldn’t be willing to veer from the motions they’ve spent their careers refining. Cortes does so without a second thought.

“I think he’s sneakily extremely athletic,” said Taillon, noting that he’s “too scared” to attempt Cortes’s subterfuge. “When I watch him do these things, I pay attention to what his mechanics are doing. It’s pretty incredible that he can hesitate and kick his leg around and keep his back knee over his ankle and keep his glute locked in and just stay strong. The pitching nerd inside of me is fascinated by watching what he’s doing.”

As for deciding when to mix it up, Cortes is often left to his own devices. It’s very much a feel thing, and the situation plays a role. Two-strike counts after a few standard pitches are fouled off make for optimal times, but hitters know that Cortes is unpredictable.

Sometimes Higashioka will signal for deceit, but the catcher no longer has to nudge the pitcher. Cortes’s so-called “normal” offerings have improved, but he has no plans of abandoning his unusual ways.

Not this time.

“I’m true to who I am,” Cortes said. “I understand who I am as a player, as a pitcher. And if it’s working right now, I don’t see why I should be changing anything.”