The seams sizzle across the diamond as the baseball slices to first base. Major league ballplayers make it look easy, as if they aren't even trying. But don't be fooled. Their ability to throw is firmly cemented in the fundamentals.
Get a Grip
Roll the ball in your hand until the seams resemble an Indianapolis Colts logo, or an open-side-down horseshoe. Both sides of the horseshoe make up two of the four longest seams on the ball. These are known as the four seams. Turn the ball and place the pads of your index and middle fingers on one of the four seams. Throwing with a four-seam grip will help the ball stay straight through the air. You can use your fourth finger too if your hands are smaller. Anchor the grip with your thumb underneath the ball and curl your other fingers out of the way. Grip the ball lightly and keep a loose wrist throughout the throw.
Imagine a line running straight through both of your shoulders, and through your collarbone. Turn your body so that line points at the target through your glove-side shoulder. Stand with feet shoulder width apart and toes facing perpendicular to the target. Step with your glove-side foot to the target while pushing off using the entire length of the inside part of your back foot. During the stride, your front foot should open up and land with toes facing your catch partner. Avoid landing on your heel. Land on the ball of your foot or on an entirely flat foot.
Separate and Load Up
When the stride begins, you need to separate your hands; take the ball out of the glove with your throw hand. The glove arm raises out in front of you during the stride. Point the glove at the target and use it like a gun sight, visually lining up the target down the length of your outstretched arm. Meanwhile, the throw arm needs to load up into a cocked position simultaneously. Raise the ball behind you, making a backward L with a 90-degree hinge at the elbow. Your arms should reach the top of this ready position just as your front foot strikes the ground.
Now you're ready to throw the ball. Use the momentum of the stride to take your throw hand to the target as straight as possible and don't stop that momentum until the ball is well out of your hand. Throwing a baseball properly will cause you to bend over slightly with your arm whipping across your body. Your back leg should come up off the ground, forcing you to balance on a stiff front leg. To avoid injury, use your arm like a whip. Get your hand to the target with a light, quick motion and don't try to stop your arm with any rigid strength.