PHILADELPHIA -- Asked this spring in Clearwater, Fla., for a quick demonstration, five Phillies starters grabbed a baseball and instinctively positioned their fingers to illustrate how they throw one of their bread-and-butter pitches.

This, they explained, is how they throw a curveball.

“Everybody has a different grip,” Phillies ace Aaron Nola said. “Every curveball is different.”

No rotation in baseball last season threw a higher percentage of curveballs than the Phillies. They threw 3,034 overall, or 21.1% of their total pitches thrown. (The Rays also threw 21.1% curveballs, but only 2,391 overall.) We thought it would be fun to ask every starter how they throw theirs and tell the story behind it.

Before Spring Training got cancelled in March because of the coronavirus pandemic, we talked to five of the seven starters, either already in the rotation or competing for a job in the rotation: Jake Arrieta, Nola, Nick Pivetta, Vince Velasquez and Zack Wheeler. We missed Zach Eflin, who threw his curveball only 5.4% of the time and is known more as a sinker-slider guy, and Ranger Suárez, who did not throw one at all.

The basic mechanics behind each curveball are similar: the palm of the hand is turned toward the head as the pitcher throws, which allows him to pull down on the ball to get the spin he needs for a sharp downward break. But each one has subtle differences. Each one is unique.

Jake Arrieta

If you want to know why hitters sometimes buckle their knees when a pitcher throws a curveball, it’s because the pitch looks like a fastball out of the hand and the hitter thinks it’s headed toward his neck. Then, of course, the ball breaks toward the zone.

Reactions like that make curveballs fun to throw.

“When it’s on, yeah,” Arrieta said. “When you can get a little knee buckle, it’s a good feeling. These guys see good curveballs night in and night out. And when you get that little hesitation, that little jelly leg from a hitter, that’s a good feeling.”

Arrieta’s curveball has more movement and spin than most in baseball, moving slightly more vertically (1.8 inches more than average) and much more horizontally (6.0 inches more than average), according to Statcast. His spin rate is in the 85th percentile. The more spin on a curveball, the better. Curveballs with a higher spin rate are more likely to be hit on the ground.

Arrieta’s father taught him the foundation of the breaking ball. Arrieta fiddled with his curveball grip over the years. Today, his middle finger rests along the right seam of the U-shaped horseshoe. The pad of his index finger rests just above the bottom of the “U,” which faces into his hand. It looks like a spike-curveball grip, but Arrieta emphasizes that he does not put intense pressure on the index finger, like most spike grips. His thumb rests on the opposite seam on the bottom of the ball. Arrieta uses both the middle finger and the thumb to pull down on the ball.

Arrieta’s lower arm slot gives the ball more of a 1-7 break, if looking at home plate like a clock face. Sometimes he gets a 12-6 break.

“When I’m going well, it kind of becomes more of a 12-6,” he said. “Any time you can get more downward action on any of your pitches, it’s going to be more effective.”

Arrieta’s 1-7 break works well, too. Last season, opponents batted just .204 with a .256 slugging percentage against it.

Aaron Nola

If the season started today, Nola probably could throw a few nasty curveballs. He has one of the best in baseball.

It wasn’t always that way.

“When the seams started getting a little smaller in the Minor Leagues, I was kind of struggling with it,” he said. “It was kind of backing up on me. I was playing around with a spike curveball on flat ground. I started moving that [index finger] up and started throwing it in some [throwing sessions on] flat [ground]. I saw it kind of moving a little bit, a little bit more. I threw it in a game and the first hitter of the game kind of buckled a little bit. I told myself, 'I’ve got to stay with this.'”

Nola got 445 called and swinging strikes on curveballs last season, which led baseball. He got 109 strikeouts on it.

Perhaps the ultimate compliment is that hitters are helpless against it, even though they know it is coming. Nola threw his curveball 35.2% of the time last season. Only four pitchers (minimum 1,500 pitches) threw a greater percentage than him. His breaking ball moved vertically 3.0 inches more than average. It moved horizontally 1.9 inches more than average. Hitters cite the pitch’s late break for its effectiveness.

“I want that second break,” Nola said. “I want it to break, then break hard down.”

The open part of the horseshoe sits deep into Nola’s palm, which gives him the feeling that he has more seam to work with. The middle finger runs along the right seam. His index finger serves as a guide, sitting in the middle of the two seams.

“I needed something harder with more control, so I started gripping it like that,” he said. “It’s a little bit tighter. It’s actually easier to command for me. Then when I’m kind of struggling with it, I go back to throwing the football curve [on flat ground]. It kind of keeps me on top of the baseball with my finger on top so I can pull down.”

The “football curve” is the breaking ball that Nola’s father taught him when he was about 11 years old.

“You don’t break your wrist,” Nola said. “I’ve never thrown a slider, but I think you break your wrist a little bit more. But he always told me, ‘Don’t break your wrist.’ You can throw it, stiff wrist, just like a football. You don’t see a lot of guys getting elbow injuries throwing a football.”

Nick Pivetta

Pivetta listened when former Phillies pitching coach Bob McClure suggested he change his curveball grip in 2017.

McClure pitched 19 seasons in the big leagues. He coached for more than 20. He knew that Pivetta’s secondary pitches needed help. MLB Pipeline said at the time that Pivetta threw “both a slider and curve, but they tend to run into each other.” One day McClure showed Pivetta a spike grip. Pivetta held the baseball with the bottom of the horseshoe facing him. His middle finger ran along the right seam. He dug his index finger into the MLB logo. He threw a few. It felt comfortable immediately.

Flash forward a few years: A lot of people thought Pivetta was destined for a breakout 2019 season in part because his curveball became such an excellent pitch. Its spin rate last season ranked in the 92nd percentile. It broke vertically 6.2 inches more than average. It broke horizontally 3.6 inches more than average. Wheeler said Pivetta’s curveball is special because it “tunnels” the same as his fastball. Essentially, when Pivetta throws his curveball, it looks like a fastball out of his hand. There is no bump there. Hitters have nanoseconds to recognize a pitch and decide to swing or not. Pivetta’s ability to make his fastball and curveball look the same when he releases it gives him an advantage.

“When it’s good, it’s tunneling,” Pivetta said. “The biggest thing is picturing Brandon Morrow’s curveball when he was a starter with the Blue Jays. That’s what I strive for. I don’t think it’s that good, but that’s an incredible curveball. It comes out and it comes straight down. I strive for something like that.”

Opponents had a .263 wOBA vs. Pivetta’s curveball compared to sliders (.322), four-seam fastballs (.466) and sinkers (.549). Pivetta threw his breaking ball 35.2% of the time, tying Nola for the fifth-highest percentage in baseball.

“What happened last year is I threw it too much,” Pivetta said. “Then it was really inconsistent and then I didn’t have anything else to back it up.”

He worked this offseason and spring to throw a changeup. If it plays, it could make his curveball even more effective.

Vince Velasquez

Velasquez threw knuckleballs more than curveballs growing up. His Tim Wakefield impression stopped once Houston selected him in the second round of the 2010 Draft.

“I knew how to throw [a curveball],” Velasquez said. “I knew how to throw it in high school. I just never really fiddled with it. Maybe occasionally to the point that I could throw a get-me-over curveball. But it wasn’t anything spectacular until I got in the Minor Leagues. It just wasn’t my go-to pitch.”

Velasquez first threw a curveball with his index and middle fingers running along a seam. Class A Lancaster pitching coach Don Alexander showed him a spike grip in 2013. Velasquez holds his differently than Nola and Pivetta. While he has his middle finger run along the right seam of the horseshoe, he digs the fingernail of his index finger into the seam on the bottom of the U.

“You’re just pretty much like flipping it,” Velasquez said. “Think of like flipping the ball. The amount of spin you put on the ball will determine how much spin you enforce. That’s what you’re doing with that middle finger. You’re snapping it, so you’re pretty much forcing it. If you’re forcing that forehand rotation, I mean, you’re getting a lot of spin on it.”

Velasquez threw 30 curveballs (26.5%) when he pitched his 16-strikeout shutout against the Padres in April 2016. He threw curveballs only 12.2% of the time last season, the lowest rate of his career. The percentage jumped to 24.2% in September, which might be a sign of things to come in 2020.

Zack Wheeler

Wheeler’s father taught him how to throw a curveball on the mound at his Little League field, although he could not throw it in games until he turned 11 or 12. His father wanted him to first learn the proper technique.

“It got me going and thinking about it,” Wheeler said.

Every Phillies fan has heard something about Wheeler’s curveball since the team signed him to a five-year contract in December. It is an excellent pitch. It is excellent in part because the speed differential between his four-seam fastball (96.8 mph) and curveball (80.7 mph) is so extreme. Its spin rate ranked in the 71st percentile, and the pitch averaged 2.3 inches more movement vertically. Opponents had a .245 wOBA against it, compared to his slider (.275), changeup (.275), four-seam fastball (.281) and sinker (.345). Since 2017, opponents had a .211 batting average, a .303 slugging percentage and a .252 wOBA against it.

Still, Wheeler threw his curveball only 10% of the time last year. Expect that number to increase.

Wheeler’s grip is different from others. The bottom of the horseshoe faces into his hand and he places the middle finger on the right seam so he can pull down on it. But unlike Arrieta, Nola, Pivetta and Velasquez, who spike their index fingers to varying degrees, Wheeler places his index finger next to his middle finger.

“I’ve only heard of one other guy [in Phillies camp] holding it like that,” he said. “I was like, ‘Wow, you’re the first guy I’ve seen that holds it like that.'”

But why try anything else? It works.

“I usually always have my curveball,” Wheeler said. “I’ve just got a good feel for it. Nothing really changes with the grip. Even with a fastball, sometimes it feels like a little off, just because your fingers might be a little weird that day. But the curveball, it’s always going to be there. I don’t know why, but it is.”