The pitch that has vaulted Gio Gonzalez into baseball’s elite was learned in a narrow, partly grassy patch between his childhood home and his neighbor’s house in Hialeah, Fla. He was 13, and his father, Max, an astute observer of baseball, wanted his son to learn a new pitch because his fastball, at the time, was average.

The mound was the gray metal generator. Gonzalez stood in front of it and behind a strip of concrete floor, a stand-in for the rubber on the mound. Max set up as the catcher in front of the wooden fence at the far end near the street and instructed his son: Throw the curveball with the same force as your fastball, get your fingers on top of the ball and do it until you find a comfortable grip.

“I’d throw it and throw it and one day I just got so fed up with, ‘You’re not throwing it right, you’re not throwing it right,’ ” Gonzalez said. “And I just started throwing and slinging and I wanted to throw it as hard as I can and snap it.”

And with that, perhaps the best left-handed breaking ball in the major leagues was spawned. There, Gonzalez found his own unconventional grip, began mastering his textbook mechanics and deceptive delivery, and started on his path to becoming a leading candidate for the National League Cy Young Award this season.

The Washington Nationals forked over four top prospects last winter to acquire the pitcher from the Oakland Athletics, a hefty price for an all-star still learning to harness his prodigious talent. But Gonzalez, 27, has exceeded all expectations. He was the first pitcher in the majors to 20 wins, one of the majors’ best left-handers, the Nationals’ unquestioned ace without Stephen Strasburg and their Game 1 starter in Sunday’s National League Division Series against the St. Louis Cardinals. His wicked, hard and disappearing curveball is a major reason why.

Gio Gonzalez confounds batters by throwing all four of his pitches with nearly identical arm motion and position.

“It’s the best left-handed curveball in the big leagues,” said former pitcher Dan Plesac, a three-time all-star and now an analyst for MLB Network.

Deception is key

Pitching relies heavily upon deception. Batters look for any clue to help them figure out what a pitcher will hurl at them: the rotation of the ball, the location of a pitcher’s arm, any difference in mechanics. Gonzalez’s best trait, pitching experts say, is that there’s no perceivable difference between how he looks when throwing his curveball and his fastball.

“If you could overlay all three of Gio’s pitches — fastball, breaking ball, change-up — the positioning of his arm is nearly identical,” said Tom House, a renowned major league pitching coach. “It’s what happens the first four feet out of the hand that makes it so hard for a hitter to see, read and commit to the pitch.”

Gonzalez achieves that with arm speed and consistent arm position. The same force that he uses to fire his lively 94-mph fastball he uses to throw his devastating 80-mph curveball. The whip of the arm is the slingshot that gives the ball the speed and wicked spin. Gonzalez also keeps his arm in the same three-quarters slot for every pitch.

“A lot of times with curveballs, more than any other pitch, it will go above the fastball plane,” House said. “And if it goes above the fastball plane, then the hitter knows it’s not a fastball.”

Batters also often look for the red stitches on the ball for clues. If a breaking ball isn’t spinning tightly, a batter will see a glob of red. Less rotation means less movement on the ball, and it will be slow enough for a batter to figure out what pitch was thrown. But if the ball is spinning quickly, a batter sees less red and mostly the white of the ball. In the split-second reaction time of hitting, even a minor slip-up can be magnified.

“The difference between a good curveball and a bad curveball, in layman’s terms, is the rotation on his curveball,” Plesac said. “It’s so quick and it spins so quick, that it’s hard for a hitter to pick up.”

While curveballs can be slow and have wide, looping bends, Gonzalez throws a harder variation. His average curveball is 79.8 mph, the ninth fastest among major league starters, according to pitching data collected on He throws it nearly 21 percent of the time, the seventh most among qualifying starting pitchers. (That’s actually a lower percentage than in previous seasons because Gonzalez learned how to use it more effectively.) The curveball breaks late and sharply, as it nears the large dirt circle around home plate. He struck out 207 batters this season, fourth-most in the NL, many with his curveballs.

But what makes the curveball more dangerous is its pairing with Gonzalez’s fastball. Part of deception in pitching is varying speeds, and there’s no bigger difference than between a fastball and curveball. Gonzalez’s average fastball is 93.1 mph, the 11th fastest in the majors. And he throws it a lot: nearly 71 percent of the time, third most in the majors. Gonzalez also thrives on nibbling on both the inner and outer portions of the strike zone.

“That curveball is that much more effective off a mid-90s fastball, especially when it seems like he is comfortable throwing it pretty much any count,” New York Mets third baseman David Wright said. “So when you go up there, it’s tough to look for 94-, 95-mile-per-hour fastball.”

‘It clicked and it worked’

While there are time-tested ways to teach how to throw a pitch, each pitcher tweaks the grip and delivery on his own. Gonzalez fiddled with every sort of grip on his curveball. He tried it the traditional way, where the index and middle finger intersect the tip of roundest curve of the laces. It didn’t work.

“I was stubborn and hard-headed at the time,” he said. “I didn’t want to learn the basic way of everyone throwing the pitch. Because you get that circle dot in the middle and I want to change it up and do something different and make it look exactly what it was, a fastball. And then it dropped, it clicked. Whatever my dad taught me, I never went against it. Someway, somehow, it clicked and it worked.”

Gonzalez moved his fingers around the ball until the grip felt comfortable and the ball had dramatic movement. What felt the best was when he placed both index and middle across over the heart of the ball, crossing two laces, almost like most would hold a four-seam fastball. And when he threw it, with his quick arm whip, he squeezed his fingers together and the ball dipped like it does now.

“The grip is what confused everyone,” he said. “No one understood it.”

Generously listed at 6 feet tall, Gonzalez gets his power from his legs and hips. He has a twisting delivery, in which he bends his torso back toward center field, brings his front leg high between his clasped hands and unwinds like a coil. It’s a long, smooth delivery, and the ball rockets out of his hand. “Gio is more like a rubber band,” his father said.

A hitter can’t see the ball until Gonzalez’s arm appears, extended far out to his left. He releases the ball just past his left ear. As a result, Gonzalez has both real velocity and perceived velocity, House said.

“It’s closer to home plate so his perceived velocity looks harder than it actually is,” he said. “You can add two or three miles an hour to whatever the gun says with his delivery.”

In his first year in Washington, Gonzalez earned his second all-star selection, helped power the Nationals to Washington’s first playoff appearance since 1933 and is slated to be their No. 1 starter in the playoffs. He has done so because he perfected one of baseball’s most difficult pitches.

“Not that many people throw good curveballs anymore because a slider and a cutter are easier to master,” House said. “They’re easier to throw strikes with right away. But the kids who stay with the curveball long enough through amateur ball to collegiate ball, you get mastery of the curveball. Those kids that throw curveballs for strikes, they usually pitch for a long time.”