Jeff Gordon has been reporting and writing since 1977. His most recent work has appeared on websites such as eHow, GolfLink, Ask Men, Open Sports, Fox Sports and MSN. He has previously written for publications such as "The Sporting News" and "The Hockey News." He graduated from the University of Missouri-Columbia School of Journalism in 1979 with a bachelor's degree.

This is also important for throwing a fastball and other pitches as well.  What do I mean when I say stay behind the ball?   It means don’t be under the ball, too much to the side of it, or overdoing it with your wrist or elbow. Regardless of your arm slot, you will properly get to this point in your delivery by doing everything correctly with your mechanics from the ground up.  From the time your feet first move to deliver the pitch.  
You may already know about the risk of sustaining an overuse injury to the pitching arm, from repeated movements. For that reason, upper body drills shouldn't place excess stress on the shoulders. This is a very simple exercise that gently stretches the rotator cuff, and doesn't require any special equipment. This a great exercise for loosening up the shoulders before practices and games!
For the second phase of this shoulder prevention pitching drill one athlete will continue facing forward while the opposite athlete turns to face their partner. Athlete facing their partner will be performing the should prevention portion of this phase of the pitching drill while partner the facing forward will be focused on strengthening their core.
When thrown, try to manipulate the pitch to come off of the thumb-side of your index finger – NOT your index- and middle-fingers, as with a two-seam fastball – because a two-finger release will cause the pitch to balance out, which reduces the spin that you are looking for. Most good slider pitchers grip the outer-third of the baseball and cock their wrist slightly, but not stiffly, to their throwing hand's thumb-side upon release of the pitch. This enables a pitcher to apply pressure to the outer-half of the ball with the index finger. Avoid any twisting of the wrist upon release.
Great baseball pitching is your team's first defense. So it's important your pitcher be their best. But while you may think good pitching involves natural talent, think again! There's no question that a laser lob calls for lots of balance, strength, agility, speed, and accuracy. With the right drills, any pitcher can accomplish that. Effective pitching is a learned art. Understanding the mechanics of pitching from the ground up, and choosing drills that fine-tune both the lower and upper parts of the body are sure to take your pitcher from average to ace!
To throw start with your dominant hand facing away from the catcher facing sideways.  Bring up your front leg.  When you do this at the same time bring up your throwing arm with the ball facing away from the catcher 90 degrees to your shoulder like an L shape.  Then bring your arm down to your knee and release at the time necessary.  It should look something like the video.  He doesn't bring his arm and leg up at the same time but everyone's throw is a little different.
Next, place your middle finger along the bottom seam of the baseball and place your thumb on the back seam (as shown in the middle picture above). When this pitch is thrown, your thumb should rotate upward, and your middle finger should snap downward while your index finger points in the direction of your target. This, of course, is the reason this pitch is great for beginners: the ball goes where your index finger points. The beginners curveball helps to align your hand and ball to the target.
It's always best to learn proper pitching mechanics early -- and then continue to refine those mechanics as a player gets older and advanced in the game of baseball. This starts in little league. These little league pitching drills can be used as a teaching and training tool to promote and develop proper pitching mechanics. Each little league pitching drill focuses on a specific aspect of the pitching delivery, allowing the pitcher to develop a feel for good mechanics that directly translates into better consistency in games, more strikes and increased pitching velocity.
Throw this pitch with the same arm speed and body mechanics as a fastball, only slightly turn the ball over by throwing the circle to the target. This is called pronating your hand. (Think about this as giving someone standing directly in front of you a "thumbs down" sign with your throwing hand.) This reduces speed and gives you that nice, fading movement to your throwing-arm side of the plate.
Asking if a kid can see that slider spin is occurring is a common question I will bring up in lessons. Having a thought process and feeling with what they are doing is something that he or she can control and fix from throw to throw but it is not often taught. We like to have kids visualize and react to what is being said and into what is being felt. When trying to recognize the slider spin, the catcher should be able to see where the thrower is missing with his fastball. Seeing the ball out of the thrower’s hand and knowing that a slider has clockwise spin on the baseball you will be able to clearly tell that they released the ball wrong.
The Curveball is generally a more advanced pitch to learn and throw because of the unique mechanics involved. Many coaches feel that younger players (below the age of 15) should not practice throwing the Curveball with real baseballs because it might place too much stress on a young arm. Although it is likely much safer to throw curveballs with a Blitzball because of its light weight, younger players should still ask parents' for their approval before trying to learn it (you might want to learn a hard Knuckleball instead to get a similar dropping action without having to throw actual Curveballs). The Curveball is unusual because it is the only pitch that involves "topspin" (think of it as the opposite of a fastball's backspin).

For example, physical forces and properties, such as gravity, friction, velocity, acceleration, and momentum, are constantly at work when a ball is thrown and subsequently hit by a bat. When it comes to a curveball, though, the spin put on the ball by the pitcher brings a couple of other scientific principles into play: Bernoulli's principle and the Magnus Effect.
No two pitchers ever throw exactly the same, but their deliveries share three components: balance, timing and power. (See how to work on some of these: The Keys to Improving Pitching Speed and Power.) Every good pitching drill must address at least two of these components. It also must be tailored to your individual style. For example, say you specialize in sidearm pitching. A drill that teaches throwing downhill and forward trunk tilt would be a waste of your time.
3. Elbow: The throwing elbow must be equal to or slightly above the throwing shoulder. As soon as the pitcher lowers the elbow below the shoulder, they put additional stress on that arm. The angle of the elbow joint should be no more than 90 degrees. Pitchers who throw curveballs at angles greater than 90 degrees may put additional stress on their throwing shoulder.
See, ultimately when you use it in the game, you do want to throw your curveball with good arm speed and hand speed (or good fastball tempo). But the problem is, if you’re not used to throwing a baseball with the correct curveball hand and wrist position (supinated – palm turned in), chances are you’ll have a tough time maintaining it through ball release.  Your hand is going to want to revert back to the way it’s used to throwing.
The arm swing and finish is the hardest thing to correct in a thrower besides having a feel for which finger the ball is coming off of through the throw. Lucky Baseball Rebellion has developed some fairly simple concepts to allow your child to efficiently enhance upper body mechanics and arm swing.  Here is a #TransformationTuesday tweet from Baseball Rebellion showing how a forty minute lesson can help your son or daughter with arm swing mechanics.

House primarily talked about kinematic sequencing, essentially developing good timing in your delivery.  The part that was most interesting to me was when he got into the idea of reprogramming movement patterns, or replacing old movement patterns with better ones His main point was that if you want to make lasting changes, you really need to break it down and go back to the early stages of development.

A pitcher's should stride at a minimum 80% his height towards home plate during his fastball delivery. On the curveball and change-up, his stride should be six to eight inches less than his height. For example, if a pitcher is 5 feet, 10 inches tall, then his stride toward home plate on the release of the baseball should be 5 feet, 2 inches (or thereabouts).