|MadSci Network: Physics|
The low inside pitch is typically considered a good hitting pitch by power hitters provided that the hitter can catch up to the speed of the pitch.
A well hit baseball is a complicated function of swing component timing (wrists, hands, bat), location on the bat (sweet spot versus not), and pitch location. Now thrown in human variation, and it gets very complicated. You may wish to view previous answers posted to The Mad Scientists Network on the mechanics of the baseball bat swing.
All that said, there are three principle reasons why hitters consider low and inside a "home run" pitch.
First, baseball fields are designed so that the distance to the foul poles is shorter than the distance to center field. A hitter is more likely to pull an inside pitch so the ball will travel to a shorter part of the ball park. On a level swing a batted inside pitch will tend to hook foul because of the effect of spin on the ball. However, on a low inside pitch (almost like a golf swing), the spin on the ball will be closer to true backspin and can aid in generating lift on the ball -- which results in greater distance.
Second, the bat can usually be swung faster closer to the body. For a low inside pitch the batter gets a small boost in bat speed from moving the bat downward with the help of gravity. Some people claim that a golf swing is much more natural for the body and can result in greater torque and swing speed because the pull of gravity is closer to the plane of the swing. When a batter swings a level bat gravity is pulling perpendicular to the plane of the swing requiring some amount of effort on the batters part to counter-act it. On a low inside swing, the force of gravity is much more parallel to the plane of the swing.
Third, batters are creatures of habit. From my personal experience, I love a low inside slow pitch softball pitch because I can really "turn on it." Or in otherwords, I can be much more aggressive with my swing and swing much harder without hurting myself. Batters learn what sort of pitches that they can hit well, and many find that low and inside is as friendly for success as a belt high fastball. If the batter can get to the low inside pitch in proper position the ball is going to sail.
Tom "Still Swinging for the Fences" Cull
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