The difference between a curveball and a slider is speed and shape. A curveball is slower, usually in the mid to upper 70s in MLB, and breaks in a big, looping arc that mostly drops. A slider is harder, usually in the mid 80s, and breaks shorter and later, mostly sideways. Curveballs are thrown with topspin by snapping the hand over the ball, while sliders get sidespin from a grip and release more like throwing a football. The chart below compares them head to head and shows the whole breaking ball family.
| Curveball | Slider | |
|---|---|---|
| Typical MLB speed | Mid to upper 70s mph | Mid 80s mph |
| Break | Big, looping, mostly downward | Shorter, sharper, mostly sideways and late |
| Shape out of the hand | Pops up out of the hand, then drops | Looks like a fastball, then darts |
| Grip | Middle finger along a seam, thumb opposite | Off center grip, ball held toward the outer half |
| Release | Hand comes over the top of the ball, snapping forward | Like throwing a football or turning a doorknob |
| Spin | Topspin | Mostly sidespin with some gyro spin |
| Best use | Steal a called strike or get a swing over the top | Get chases off the plate and swings and misses |
| Hardest part | Commanding it for strikes | Keeping it from flattening out |
Which Is Easier to Learn?
Many coaches consider the slider easier to throw hard, since the arm action is close to a fastball, while a good curveball takes more feel to command. For young pitchers, most youth coaches recommend mastering a fastball and changeup first and waiting on breaking balls until the body matures; MLB’s Pitch Smart guidelines cover pitch counts and rest for every age.
Why Sliders Took Over
Over the last decade, sliders and sweepers have become the most popular breaking balls in MLB, passing the curveball. They generate more swings and misses and chases off the plate, and pitchers can throw them harder. The curveball remains valuable for stealing early strikes and changing a hitter’s eye level, and many pitchers throw both.