Let the ball sit deeper.
The ball can sit deeper than a fastball to load the pull-down feel.
The fastball, mirrored.
12-6 curveball
Topspin instead of backspin, so the Magnus force points down and joins gravity. It falls straight, 12 to 6, far more than a spinless ball would.
Specimen 03
seam-informed schematic
Sourced, not corrected
01Grip Lab
View
Hand
Drag to inspect, or use the View buttons
The drop / 03
12-6 curveball
It falls straight off a table, twelve o’clock to six. Same arm speed, late and hard.
Ball depth
Deeper in the hand
Spacing
Fingers close
Thumb
Thumb anchors the back seam under the middle finger.
Release feel
Middle finger pulls down through the front of the ball to create topspin.
The ball can sit deeper than a fastball to load the pull-down feel.
Palm gap cue
- Middle seam / Primary curveball pressureLeverages the seam for the pull-down. This finger owns the pitch.
- Index light / Light guide or spiked variantRests beside the middle finger. Minimal pressure.
- Back thumb / Opposes the middle-finger pullUnderneath on the back seam. Anchor under the seam.
See it live / via @PitchingNinja
The grip is the cause. This is the effect, the same pitch shot in a real bullpen. Sourced, not corrected.
- 1Run your middle finger along a seam and rest your thumb on the back seam, the ball pinched between them.
- 2Let your index lie alongside with almost no pressure, or tuck its knuckle for a sharper bite.
- 3Throw the front of the ball, not the back. That is what makes the topspin.
- 4Keep fastball arm speed and pull down hard and short, like chopping straight down.
Get on top and pull down through the front of the ball. Stay over it; finish short.
The sourced grip, in full
The hand gets on top of the ball so the fingers impart pure topspin. The middle finger leverages a seam, the index rests on the leather beside it, the thumb sits underneath on a seam, and the ball is tucked back toward the palm to load spin.
Reputable analysisDriveline Baseball, How to Throw a Curveball
Paraphrased from Driveline, not quoted. Spike and knuckle variants are a common feel-based alternative.
Driveline's standard curve grip leverages the middle finger on the seam with the index on the leather and the thumb on a seam underneath. Topspin comes from getting the fingers in front of the ball and pulling down, the cue being to yank it down with the middle finger.
Reputable analysisDriveline Baseball, How to Throw a Curveball
Paraphrased. Spike "CB 3-4" variants live on the same page.
The name is the clock face: the break runs in a straight line from 12 to 6. A higher arm slot makes it more vertical, a true 12-6; a lower slot tilts it toward a 1-7 slurve with more sideways movement.
Reputable analysisBaseball Monkey, How to Throw a Curveball
Paraphrased coaching reference for the clock-face naming and the arm-slot relationship.
Grip geometry is schematic and shows the straight-curve family; spike and knuckle variants change the index shape.
02Release Room
Translate the hold into a release.
Grip shape only matters if the release makes sense. This room keeps the player reading pressure, thumb support, and ball depth before movement numbers show up.
Get on top and pull down through the front of the ball. Stay over it; finish short.
middle finger owns the shape.
Primary curveball pressure
Release is a feel, not a formula.
Middle finger pulls down through the front of the ball to create topspin.
Film Room / watch a master
The schematic shows the release path. This is the release: Gibson walking through the delivery himself. Real hand, real ball, real finish, no model can fake it.
Topspin is generated by getting on top of the ball and driving the fingers over the front of it, pulling down so it rotates forward rather than with a slider's lateral tilt. Per Driveline, a higher release point leads to a more top-down movement profile, the classic 12-6, while lower slots add horizontal movement and turn it into a slurve.
Reputable analysisDriveline Baseball, How to Throw a Curveball
Paraphrased from Driveline. The fastball-mirror framing is grounded in the MLB.com IVB glossary.
03Movement translation
Topspin drags it down off a cliff.
Where the fastball spins backward, the curve spins forward. That topspin pulls the ball down late. It looks like a fastball out of the hand, then the floor drops out. A true twelve-to-six falls almost straight, with little sideways break.
The measured movement, if you want it
The curve is the four-seam fastball's mirror. The fastball spins backspin, so its Magnus force points up and it rides; the 12-6 spins topspin, so its Magnus force points down and it drops. Same physics, flipped axis, which is why a four-seam carries about +16 inches of induced break and a curveball drops about -10.
2024 MLB four-seamers averaged +16 in induced vertical break (most rise), curveballs -10 in (most drop), the mirror relationship.
Spin axis and force direction, drawn in render space
Spin rate
≈ High. The MLB-average curveball spun about 2,523 rpm in 2019; elite 12-6 curves sit well above. Kershaw runs about 2,242, and high-spin power curves like Morton's reach 3,000 and up.approx
Reputable analysisMLB.com Statcast Glossary, Spin Rate
Player and season dependent. Exact rpm from Savant arsenal data.
Active spin
85% on a clean 12-6 (Kershaw, 2024): almost all of the spin is working topspin that drives the drop.
Official dataBaseball Savant (Statcast), Clayton Kershaw/ 2024
From the Savant spin-direction table.
Induced vertical break
Large induced drop. MLB curveballs averaged about -10 inches in 2024, the most induced drop of any pitch; the biggest 12-6 curves reach -15 and beyond. Kershaw's is -15.3.
Negative induced vertical break means it drops more than a spinless pitch. The glossary names Fried, Yamamoto, and Kershaw as large-drop curveball throwers.
Horizontal break
≈ Little to none is the mark of a TRUE 12-6. Kershaw breaks only about 6.6 inches glove-side, close to straight down; curves running 10 to 16 inches glove-side read as 1-7 power curves instead.approx
Official dataBaseball Savant (Statcast), Clayton Kershaw/ 2024
Kershaw 2024 horizontal break ~6.6 in glove-side per Savant. Minimal horizontal is the hallmark of a 12-6.
Spin axis
Near-pure topspin: the axis lies roughly horizontal and points the Magnus force straight down. Kershaw's curve, the cleanest modern 12-6, sits near a 5:30 clock with 85% active spin. More glove-side tilt makes a diagonal power curve instead.
Official dataBaseball Savant (Statcast), Clayton Kershaw/ 2024
Kershaw 2024: observed 5:30, spin-based 5:15, 85% active spin, from Savant.
Topspin points the Magnus force down. It drops far more than a spinless ball, with little sideways break.
02Master files
The verified baseline.
A textbook 12-6, the curve that anchored a career beside it, and a power curve to show where the straight-down line ends. The visual is our own seam schematic; every figure is season-stamped and sourced.
Master file · 01Verified · Attributed
Clayton Kershaw
The textbook pure 12-6: almost all of its movement is straight-down induced drop with minimal horizontal run. MLB's own induced-break glossary names him as a large-drop curveball thrower.
Induced vertical break
-15.3 in
Official dataBaseball Savant (Statcast), Clayton Kershaw/ 2024
2024. Negative is induced drop, far beyond the ~-10 in league average.
Horizontal break
≈ 6.6 in glove-sideapprox
Official dataBaseball Savant (Statcast), Clayton Kershaw/ 2024
2024. Minimal horizontal, the signature of a true 12-6.
Velocity
Spin direction
5:30, 85% active
Official dataBaseball Savant (Statcast), Clayton Kershaw/ 2024
2024 observed clock, near pure topspin.
Spin rate
≈ ~2,242 rpmapprox
Reputable analysisBaseball Savant (Statcast), Clayton Kershaw/ 2024
Recent-season arsenal figure.
Master file · 02Verified · Attributed
Adam Wainwright
The "Uncle Charlie" that anchored a 200-win Cardinals career and ended the 2006 pennant on a called strike three. A true over-the-top 12-6 in his prime; as his arm slot dropped with age it flattened into a two-plane 2-to-7, the bridge between Kershaw's straight-down curve and Morton's power 1-7. He said it came out 75 mph no matter how hard he threw it.
Velocity
71.5 mph
Official dataBaseball Savant (Statcast), Adam Wainwright/ 2023
2023. In his prime he capped it near 75 by feel; by his final year Statcast had it in the low 70s.
Induced vertical break
-13.5 in
Official dataBaseball Savant (Statcast), Adam Wainwright/ 2023
2023. Negative is induced drop.
Horizontal break
16.5 in glove-side
Official dataBaseball Savant (Statcast), Adam Wainwright/ 2023
2023. Heavy glove-side run: late-career it swept as a 2-to-7, not a pure straight-down 12-6.
Opponent line vs. the curve (career)
26 wRC+
Roughly 74% below league-average offense against it over his career; 100 is average.
I could throw it as hard as I could possibly throw it, and it’s going to come out 75 mph.
Master file · 03Verified · Attributed
Charlie Morton
The high-spin power-curve contrast. Elite spin, big total drop, but heavy glove-side tilt, an 8:00 axis, so it reads as a 1-7 power curve rather than a pure straight-down 12-6. It marks where the line ends.
Induced vertical break
-8.9 in
Official dataBaseball Savant (Statcast), Charlie Morton/ 2024
2024. Less induced drop than Kershaw because more spin is tilted into horizontal break.
Horizontal break
13.6 in glove-side
Official dataBaseball Savant (Statcast), Charlie Morton/ 2024
2024. The large glove-side run that makes it a 1-7 power curve, not a 12-6.
Velocity
81.5 mph
Official dataBaseball Savant (Statcast), Charlie Morton/ 2024
2024, 1,183 thrown, his most-used pitch.
Spin rate
≈ ~3,085 rpmapprox
Reputable analysisBaseball Savant (Statcast), Charlie Morton/ 2024
2024 elite-tier; 2025 runs even higher.
Filed only when the bar is met. A real figure from the wrong tracking system, or a great arm whose signature pitch sits in a different category, gets left off rather than dressed up. The gap is the honesty.
Tier 03 / Field Notes
Field notes from the bullpen.
Every pitcher fiddles. A thumb creeps lower, a seam catches more leather, a cue from a coach suddenly makes the pitch move. Pitch Atlas keeps those experiments visible, labeled, and debated, so the small discoveries stop disappearing into group chats and comment sections.
How notes rank
Evidence and context, never who shouts loudest.
There is no single correct way to throw a pitch, but there are better and worse claims. A funny line should never outrank a tested grip. So notes do not rise on raw votes. They rise on weighted signals - provenance and adoption first.
- 35%Provenance
Source tier and evidence. A coach-observed note with a link outranks an unverified hunch with none.
- 20%Adoption
How many other pitchers independently tried the same tweak. Real replication, not passive clicks.
- 20%Usefulness
Marked useful, measured against views so a small loud crowd cannot stuff the rank.
- 15%Context match
How close a note is to your level, slot, and velocity. Computed in your session, never stored.
- 10%Community confidence
Considered practice: a real sample size behind the claim, not one good bullpen.
The vocabulary
- Field Note
- One pitcher's report on a grip variant.
- Variant
- A specific, named change from the canonical grip.
- Tried This
- A second contributor replicating the tweak.
- Coach Note
- A coach reporting on an arm they work with.
- Source Challenge
- A standing request for the evidence behind a claim.
- Provenance
- The source tier and evidence that set a note’s rank.
- Adoption
- How many others independently tried it.
- Needs Evidence
- A note flagged for missing support, kept visible.
The living layer
Field notes open soon.
Soon you will log your own grip tweak, mark the ones you have tried, and flag anything off, anonymously or under a handle you keep. When the community layer opens, every note will carry a source and confidence label, a content filter will block abusive language, and any note can be flagged. A note hides automatically once enough people report it.
When they open, every community variant will carry the same source and confidence labels as the records above. Nothing appears here unsourced, and no count is shown until it is real.