This drill is a pitching drill in which the young pitcher works at a smooth, rather fast pace, but only throw 50-60%. He should not be allowed to throw full speed. The objective of the drill is to teach concentration and develop great control. The pitcher has to throw 20 strikes before he throws 4 balls. He should be allowed to perform the drill at a shorter distance at first but he should be able to move to his regular pitching distance within a couple of weeks. If he throws 4 balls, he must start over. Be careful to not overwork him. However, keeping the distance short, emphasizing accuracy not speed, and making sure he proper stretches and warms up should prevent any chance of arm injury. With younger players you may want to make the drill a 10-3 drill. He must throw 10 strikes before he throw 3 balls or he must start over.

A Hall of Fame pitcher famous for his slider was lefty Steve Carlton. Right-handed pitcher David Cone was famous for his slider, which he was able to use many different ways, as was Bob Gibson of the Cardinals. To right-handed batters, Cone would throw it to hook sharply outside the strike zone, getting hitters to chase and miss it. He threw the pitch from various arm angles to further confuse the hitter. Cone's slider was also a strikeout pitch to left-handed hitters, throwing it to curve back over the outside corner and catch the hitter looking. Cone used the slider effectively during his perfect game on July 18, 1999—the final out was recorded via a slider resembling a wiffle ball. In the first game of the 1988 World Series, Dennis Eckersley tried to strike out Kirk Gibson with a backdoor slider, but Gibson was sitting on that exact pitch and hit a game-winning home run. Joe Carter ended the 1993 World Series with a home run on a slider thrown by Mitch Williams. A remarkable slider was John Smoltz's, which would come in looking like a strike and then break out of the strike zone. Brad Lidge featured a slider in his perfect season as a closer in 2008, and used the pitch to strike out the final batter of the 2008 World Series for the Philadelphia Phillies. Closer Francisco Cordero also throws a slider.[citation needed] Other top pitchers to throw a slider included Hall of Famer Rollie Fingers, who used the pitch to win a Cy Young Award in 1981,[1]and Seattle Mariners and Arizona Diamondbacks starter Randy Johnson, whose slider's lateral movement eventually spawned its own nickname, "Mr. Snappy". At times, Johnson's slider was faster than most pitchers' fastballs. Mike Jackson, who tied Paul Assenmacher with the most games pitched in the 1990s (644), also threw a slider. Ron Guidry threw a slider, which he was taught by Sparky Lyle.
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).
The difference between a slider and curveball is that the curveball delivery includes a downward yank on the ball as it is released in addition to the lateral spin applied by the slider grip. The slider is released off the index finger, while the curveball is released off the middle finger. If the pitcher is snapping his wrist as he throws, and the movement is more downward than sideways, then he is probably throwing a curveball or slurve, and not a true "slider".
To perform tuck jumps athletes will jump as high as they can in the air, while airborne athletes will tuck their knees into their chest. These jumps should be performed consecutively jumping, landing and immediately jumping back into the air and tucking the knees. Athletes cannot allow the resistance to alter their body positioning and need to maintain good spacing between the knees so the knees, hips, and ankles are all aligned. Athletes will perform 8-12 resisted tuck jumps for 3-4 sets before removing the Kbands and performing 2-3 unresisted sets of 8-12 repetitions.
So, when their focus is on adding extension to the delivery and trying to “reach out”, trunk rotation suffers. Because the pitcher is focused on arm extension (the idea of “reaching out”), his body exaggerates that action and forgets that upon landing the trunk must begin rotation followed by flexion in order to maximize all transferred energy so the arm gains maximum velocity.
Launching a great pitch requires good timing, and lots of control during the leg kick. New pitchers tend to fall forward too soon on follow-through, rather than staying on top of the baseball. This balance drill gets pitchers to practice holding their leg kick before full delivery. It keeps the pitcher in a position to maintain control, rather than rushing the follow-through. Slowing down the leg kick will ultimately help a pitcher to deliver straighter, faster balls, with more power and poise.

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.
A great drill for working on curveball rotation is the snap drill. It can be done anywhere as long as you have a baseball. Take your curveball grip and snap your fingers, making the ball pop straight up from your hand. Really emphasize the pull-down your middle finger creates on the ball. As the ball rises out of your hand, you should see good vertical rotation and minimal horizontal rotation.
I didn’t add this into one of the original 13 best baseball drills only because I already mentioned it above.  This is in the first video where I share my two favorite baseball pitching drills.  But I figured I post this video too because I explain it in a little different of a way.  So, if it helps someone understand a little better, then good.  That’s what I’m here for 😉