If your going to take full advantage of your coaching and applied mechanics, you must appreciate and fully understand your body's balance system.
As you stand, walk, run, avoid obstacles and so forth, your body is constantly balancing itself. Your body has a built-in sense of balance to avoid falling and injuring itself. This mechanism is an "unsolicited response" that's with you constantly. Those that have experienced a stroke or similar impact, disrupt this part of the brains ability to manage balance.
To show you just how quickly your body can act and react with respect to balancing itself, do this:
-stand with both feet on level ground
-raise both arms out to each side
-raise one leg off the ground
-now notice how the foot that's on the ground is constantly shifting back and forth, acting and reacting to keeping the body stable.
Your body is almost equally divided in proportions and with good reason(s). Like the picture below will show you, your shoulders and hips are somewhat the same width (shoulders being somewhat wider), the upper and lower parts of the arms are somewhat the same length as are the upper and lower parts of your legs, with the elbows and knees being the dividing point for each respectively. Also, notice that the length of the arms goes almost down to the upper portion of the knee - almost.
These proportions in the skeleton are equal-opposites in the human body, and can work for you -OR- against you as you learn your pitching mechanics. Because, attached to this skeleton are muscles, body fat, and other appointments while pitching - your spikes and glove for example. Add all this up and you have weight and proportions that can - again, either work for you or against you. Solid coaching that points these element units out to you can enhance your learning curve as well as guard your healthy transition at each level or progress.
Regardless of how you apply your mechanics, your body will act and react to your movements, Take for example these pitchers and notice how the back leg is used to balance off the entire upper part of the body - from the hips up to the head. Also, notice how the arms are positioned to act as a fine tuning to balance off whatever ending posture each pitcher finds himself in.
Here's a front view of basically the same posture. Notice the arms are slightly different in his ending posture - but for him, this is his way of controlling his balance.
In both cases, notice how the back leg acts as a equal/opposite balance weight to the upper body's weight shifted forward.
Below are pitcher that shift their upper body weight forward and to the side. Notice how, again, the back leg, and arms, keep the pitcher balanced. I'm not a big fan of this "Peter Pan" style of ending posture - but, some pitchers have engrained this body style to the point that it works for them.
Good balance techniques can be coached and encouraged at a very early age, if and when the player is receptive to the coaching, and the coach understands the trainee he's/she's dealing with. For example:
Finally, if your having difficulty appraising why or why not your mechanics are the way they are, possibly your fighting the natural tendencies of your body's balancing system. Of course, if your trying to pitching off a poor surface to begin with, your finished even before you start, regardless of your coaching and well your managing everything else.