Opening up the front side early as a pitcher or a hitter will spell complete disaster unless it is corrected when it is identified. When a baseball pitcher's front side opens before the front foot hits the ground, there is an inordinate amount of stress placed on the throwing shoulder because of overrotation with no protection from the front shoulder staying closed.
Performance also suffers when baseball pitchers open early. Their arm slot (whether the pitcher throws overhand, high threequarters, threequarters or sidearm) and release points will be inconsistent following poor lead arm mechanics. It leads to poor command and sub-par velocity and movement.
A baseball pitcher should never start rotating until his front foot lands. The front side will then remain closed until the back side opens it up. This technique leads to more power, better control, and a healthier arm.
Baseball hitters cannot track the ball correctly if the front foot, knee, hip or shoulder opens early. Like pitchers, a hitter should not rotate until the front foot lands. The baseball hitter will then stay on the ball and drive it with authority.