Good question. I’ll give you a simple primer on the meaning of pitches. Understand that sometimes the difference in pitches can be mere semantics – and while you’d never confuse a fastball with a curve ball, sometimes a cut fastball can be confused with a slider, and a slider can be confused with a curve ball. Now, are you confused? Yeah, I thought so.
Fastball: A catch-all term for a pitcher’s fastest pitches, be they four-seam fastballs, two-seam fastballs or cut fastballs. By the way, a fastball usually isn’t straight – it’s usually designed to have some sort of movement to it.
Two-seam fastball (or “sinker”): “Two-seamer” and “sinker” are synonymous A righthander’s two-seamer is intended to dive down and away from a lefthanded hitter, or down-and-in to a righthanded hitter. Derek Lowe of the Dodgers – formerly of the Red Sox – throws an excellent sinker. Grip a baseball with your index finger and middle finger laying on top of the seams at the seams’ narrowest point. Your fingers cross two seams… hence the name.
Four-seam fastball: This is the straightest and hardest fastball, though even it usually tails at the end. (“Tails” means a righthander’s pitch will move slightly in to a right-handed hitter and slightly away from a left-handed hitter.) Nearly every pitcher throws a four-seamer – since it moves less than the other pitches, it is often the pitch with which a pitcher has the most pinpoint control.
Grip the baseball with your fingers perpendicular to the seams at their widest point – your fingers cross the seams in four places, which is how this pitch got its name.
Some fireballers’ four-seamers are called “rising fastballs,” though whether or not the pitch actually rises is debatable… it may be that it simply isn’t as affected by gravity and doesn’t drop as much as a fastball from someone who doesn’t throw as hard.
Cut fastball (or “cutter”): A righthander’s cutter will move slightly in to a lefthanded batter and slightly away from a righthanded batter. It’s usually 2-4 miles per hour slower than a pitcher’s four-seam fastball. Watch Yankees’ closer Mariano Rivera – it’s the pitch he throws nearly every time. It can be particularly effective to a hitter on the opposite side of the plate (such as a righthanded pitcher to a lefthanded hitter), jamming him and often breaking his bat.
Slider: A slider is meant to look like a fastball, then cut and drop at the end. (A righthander’s slider will dive down and away from a righthanded batter.) It’s thrown with a karate-chop motion and the ball is released almost like you would release a football. In fact, sliders do have a “spiral” to them – the spinning laces often seem to make a red dot on the front of the ball when it’s on its way to home plate, which is how a hitter can tell what it is.
While there is certainly a difference between a pure cutter and a pure slider, many pitchers throw a pitch that is halfway between the two – with more movement than a typical cutter but not as much drop as a pure slider. In this case, the name is often interchangeable. I’ve even seen cases where the pitcher called his pitch a slider, and the pitching coach referred to it as a cutter.
Curve: A true curve ball has an over-the-top rotation and drops straight down, or drops down and across home plate. While there is a difference between a pure curve and a pure slider, sometimes a pitcher will throw a hybrid of the two, often called a “slurve.” Or he may refer to it as a curve, while his pitching coach refers to it as a slider, or vice-versa. In my experience (for whatever that’s worth), a pitcher will have more success with a true curve and/or a true slider instead of something masquerading as a little of both. If you want to see a true curve ball, watch Barry Zito of the Oakland Athletics.
Change-up (or “change”): A pitch thrown with the same arm speed as a fastball, but which comes out of a pitcher’s hand 10 to 15 miles per hour slower. It is designed to get the hitter on his front foot and either swing and miss or (often) hit the ball weakly. Trevor Hoffman, the closer for the San Diego Padres, has for many years thrown one of the best change-ups in baseball. His teammate (and former Beaver) Brian Sweeney also throws an excellent change. “Change-up,” by the way, comes from its original name, “change-of-pace.”
“Fork ball” and “split-finger fastball” (or “splitter”): While these terms are sometimes used interchangeably, in pure terms there is a difference between the two. A forkball is gripped with the baseball jammed between the index and middle fingers, and the pitch serves as a change-up, thrown with the same arm speed as a fastball while coming out of the pitcher’s hand slower and dropping dramatically. A splitter is also thrown with the first two fingers split apart, though not as far as with a forkball. A true splitter also drops, but it’s thrown harder than a fork ball.
Knuckleball: A pitch intended to have no spin – or very little spin – which can go just about any direction (sometimes more than one) on its way to home plate. It’s actually thrown not with the knuckles, but with the finger tips, and it moves because the air currents around the ball catch the ball’s laces. When thrown well, it’s difficult to hit, difficult to catch, and difficult to call a ball or strike. When thrown poorly – that is, when a knuckleball spins or stays too high in the strike zone – cue the home run music.
“Off-speed” pitch: A pitch thrown at less-than-full speed, such as a change-up or a curve ball. I confess that I’ll sometimes use this term when I’m uncertain whether a pitch was a change, a curve that didn’t break a whole lot, or a fastball, cutter or slider with a little speed taken off. I suspect other broadcasters use the term in the same way.
