This drill will help develop proper form when throwing.
Have someone standing about 5 feet directly behind the player.
The thrower should take a ball and, from the hand in glove position (as if the ball were just fielded), separate the hands with the ball hand swinging first down, then back and up until her throwing arm bicep is parallel with the ground and she has a 90 degree angle with her forearm pointing up and the ball facing backwards.
Looking at this motion from the third base side, the ball hand starts at 9 o'clock, swings down to 6 o'clock then up to 12 o'clock (if the player is a right handed thrower). If the ball is released at about 3 o'clock and the player's form is correct, the ball should be easily caught by the person standing behind her. If the ball goes to the left or right of the catcher, she is not using a proper path for her arm.
When the player has the proper arm motion, have her go into your throwing motion instead of releasing the ball. She should stride with her lead foot and follow through.
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