By Dr. John Bagonzi (edited for WebBall by Richard Todd)

Two of the breaking pitches I like very much are on the endangered species list. Perhaps because I had a pretty good one [Ed.Note: John was in the Red Sox org.], I was always partial to my Uncle Charlie, a pseudonym for the curveball, bender, roundhouse, hook, or outcurve. Or what today might be referred to simply as a big curve.

As a right-handed pitcher, I knew my curve was working when the pitch would move inside or over the plate to the right-handed hitter and then curve down and out.

From everything I see these days, this kind of so-called old-fashioned breaking pitch is on sabbatical. You just don't see it as much as you did prior to the 60's. Its once intimidating cousin, The Yellow Hammer*, has practically vanished. The Hammer is the epitome of a sharp-breaking curve - a pitch that breaks suddenly and falls off the table. Its movement resembling the darting action of the Yellow Hammer bird as it sharply dives for an insect.

The newcomers on the block are the power slider and the cutter. These new boys are good, but they are quick fixes - much easier to learn than a curveball and much more likely to be called for strikes. For those good reasons, they have become popular with the current generation of pitchers.

Oh, I've seen some pretty decent ones, and I even taught both sliders and cutters to college pitchers to enhance their repertoire and increase their survival kit. But given my druthers, I would preach Charlie to the high heavens. A well developed Uncle Charlie or Yellow Hammer is majestic and lifts pitching to an art form. These are pitches that can stun a hitter. Too often however they stun the umpire who is unwilling to recognize their brief intersection with the strike zone. Ultimately, the hitter learns that chasing such a challenging target is foolish, especially foolish when eight times out of ten they will not result in called strikes. Consequently, such rude treatment has placed Charlie and the Hammer on the endangered species list.

Let's take a look at the pros and cons of the traditional curve and compare it to the power slider, today's weapon of choice.

A curveball can be explained by way of the Bernoulli Principle. The Bernoulli Principle states that the faster an air stream moves, the lower its pressure.

With a proper curve, the ball leaves the pitcher's hand spinning. As the ball spins, the air closest to the ball moves along with it. This means that the air on one side of the ball will be moving faster than the air on the opposite side.

This also means that on one side of the ball there is lower air pressure than on the other. The slower moving air on the high-pressure side of the ball exerts greater force on the ball than the faster moving air on the low-pressure side.

The ball is then pushed to one side by the uneven pressure as it moves forward. The greater the spin, the greater the differential in pressure and the greater the break. Getting it to drop is a question of the downward trajectory from the pitcher's hand and the plane of flight caused by hand and arm angle.

And while the technique from one pitcher to another might be similar the results of any two hurlers are rarely the same.   

	CURVE	SLIDER	EDGE
Strike Zone	Hard to get over. Tough to get called strikes.	Easy to throw for strikes. More apt to be called for strikes.	slider
Break	Great two-dimensional break.	Modest break. Great rotation can give it second stage life.	curve
Batter's Read	Early break may tip it off.	Late break is hard to recognize.	slider
Receiving	Catchers may have trouble, especially when low.	Little trouble for good catchers. Easier pitch to frame.	slider
Effort	Takes time to master.	Easy to learn.	slider
Arm wear	Easier on arm.	Hard on arm.	curve
Location	Can get away with a pitch right over the plate.	Can't locate up in strike zone. Hanging slider is HR pitch.	curve
Contact	When it goes down, it is extremely difficult to hit.	Most hitters develop bat speed to hit it. It can overpower weak hitters.	curve
Versatility	Off-speed nature enables it to be used as change-up. Angle and delivery can vary.	Has to be thrown with velocity. Dependent on great rotation which won't always take.	curve