One of the most common mistakes pitchers make is relying on their upper body for the majority of their power. Even the most inexperienced coaches can see when a pitcher is using too much arm to throw.
But how do you fix it?
If you want to get the most out of your arm, you need to learn how to throw with your legs and hips. This means keeping a long stride with explosive power to foot strike. Taking it a step further, your hips have to begin to rotate before your upper body does. This way you can utilize your entire body to throw the ball instead of relying on upper body strength.
Most of the pitchers I work with start upper body rotation before lower body or hip rotation. Doing this keeps them from utilizing their entire core to help them throw.
Remember, throwing a baseball is a feet to fingertip exercise so when you put yourself in a position mechanically that keeps you from utilizing your core (like upper body before lower) you are using more arm than you should.
In this short video clip I show you just how to rotate your hips for maximum velocity.