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Don't be a knucklehead when it comes to knuckleballs (or cutters)

By Matt Albucher, Times Staff Writer
In print: Friday, October 10, 2008

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ADVERTISEMENT [BRIAN CASSELLA | Times] Right-hander Andy Sonnanstine gave up just two runs on three hits in Game 4 of the American League Division Series. Manager Joe Maddon left open the possibility of using Sonnanstine in relief early in the championship series.

So maybe you've been a casual fan of the Rays up until this point, and you're starting to pay more attention to the play-by-play when you watch on TV. But just what do they mean when they talk about "cut fastballs," "hard-breaking curveballs" and "fluttering knuckleballs"? And can a pitcher really control all that? We talked to a couple of physics professors to help us explain what you'll be seeing from the pitcher's mound this series. Porter Johnson, a physics professor at the Illinois Institute of Technology, has spent two decades researching why different pitches move the way they do. Alan Nathan is a physicist specializing in baseball science at the University of Illinois. The primary science behind all those crazy names? The manipulation of air pressure. Let's go to the chalkboard and explore.

Strike city

Here are some other pitches you'll hear about:

• Change-up: Often thrown after a fastball to throw off the hitter's timing, the pitcher uses the same arm speed as he does for the fastball, but the baseball leaves the hand at a dramatically lower velocity. The pitcher accomplishes this by pressing the baseball deep into his palm and not using his fingertips to flick the ball to home plate. Without using his fingertips, the pitcher will place less torque on the ball and lower its speed.

• Curveball: This is a fairly complicated pitch to throw because the pitcher must bend and flick his wrist while releasing the ball to create topspin. The forward spin creates an area of high air pressure above the baseball and low pressure below it (the opposite of a four-seam fastball), pushing the ball downward and producing the characteristic "break" of the pitch. If a pitcher has lots of topspin on the ball, there will be a large air pressure difference between the top and bottom of the baseball and it will have a very sharp break. A "hanging curve" can occur if the pitcher does not spin the ball fast enough. • Slider: A slider is almost exactly the same as a cutter, but thrown with less velocity, which gives the pitch more time to move as it travels to home plate.

• Knuckleball: A knuckleball might only have one rotation before it gets to the plate and is not intended to have a predictable air pressure difference on opposing sides of the baseball. The fact that it has very little spin causes the air around the baseball to become turbulent at the ball's seams, producing the characteristic "flutter" of the pitch. The pitch is usually not thrown with the knuckles, as the name suggests, but instead with the very tips of the fingers as to minimize the baseball's spin. (Note: Red Sox knuckleballer Tim Wakefield has used this pitch to great effect against the Rays in the Trop, but he's not scheduled to pitch until Game 4 at Fenway.) Spin city

The spin of any pitch is crucial in determining how the baseball moves through the strike zone. "A curveball spins in a different direction than a fastball and so does a slider,'' Johnson said. "When the ball spins, the air pressure on one side of the baseball becomes lower than on the opposing side. The ball will break in the direction of the spin." This air pressure difference occurs because the baseball's spin causes the thin layer of air surrounding it to move faster on one side of the ball than the other. The side with the faster moving air will experience lower pressure because, as a physical principle, faster-moving air has lower pressure than slower-moving air of the same temperature. In the case of a baseball, that force can be manipulated to push the ball depending on the rotational direction of a pitch.

Fast and furious

You'll hear the announcers talk about miles per hour and how fast a ball comes over the plate, but there are several varieties of a fastball, explains Nathan:

• Four-seam fastball: It gets its name from the four seams the pitcher uses to grip the ball and has a very rapid backspin as it approaches home plate. "This backspin produces high air pressure beneath the baseball and low pressure on top, giving the batter the illusion of a rising fastball," he said. The pitch is not actually rising, but is in fact falling to the ground more slowly due to the high air pressure pushing up on the baseball as it travels.

• Two-seam fastball: This allows the ball to have a sidespin as it approaches home plate. This sidespin gives the two-seamer a tailing action; the pitch will "cut in" on a right-handed hitter when thrown from a right-handed pitcher.

• Cut fastball; "cutter": "A cutter is the opposite of a two-seamer because it tails away from a right-handed batter," Nathan said. Pitchers grip the baseball as if to throw a two-seamer, but apply more pressure to the middle finger so that it spins the opposite way.

• Split-finger fastball; "splitter": A splitter is designed to fool a hitter by at first appearing to be a four-seam fastball, then sinking rapidly as it approaches home plate. The pitcher spreads his fingers so he can prevent the rapid backspin of a four-seam fastball. Without that backspin, there is less high pressure pushing up from beneath the ball and it will sink more rapidly."