Ryan Armstrong has worked at The Baseball Zone for 8 years. He is the associate head instructor, the head pitching instructor, and the director of high performance programs.
1. Consider your glove side. What does it do? Glove side is a major factor in throwing strikes! If your elbows are getting further apart as you release the ball (i.e. tucking or pulling) you will be less accurate and arm stress will increase. Instead the elbows should come closer together as we release the ball. Players must keep their glove side strong in front of them as they rotate into it. This is also known as keeping the front shoulder closed as long as possible. Make sure to bring the body to the glove, not the glove to the body.
2. Avoid repetitive mistakes. This is as simple as it gets. If you are constantly throwing the ball high, throw the ball low, even if it is not in the strike zone. Don't worry about early results, but instead concentrate on the process! I have practiced this with our athletes for many years with great success, even with first time players. This principle lets athletes know they are capable of making adjustments. Note: Smaller, more precise adjustments will come with more throwing and dedicated practice.
3. Create efficient, repeatable movement patterns. Athletes must find a set of movements that are bio-mechanically efficient and achieve the ultimate goal of throwing strikes at will. Remember, there is more than one way to pitch and everyone will be different. Note: Athletes should never slow down to throw strikes. If higher velocity pitches yield a lower strike percentage they must practice more, not slow down. The Bernstein principle of motor learning (Bernstein 1967) states: The body will ultimately organize to achieve the task at hand give enough time. Practice diligently and the changes will come!
Follow these steps and your pitchers will find they are throwing more strikes as well as throwing harder.
Ryan ArmstrongSource: http://www.thebaseballzone.ca