Expert: Steve L - 4/16/2006

Question
I have always wondered why is it that stats are kept on weather a
pitcher is left or right handed and is pitching to either right or
left handed batters?  Is it harder to hit a left handed pitcher if
you are a right handed batter? and visa-versa or what?  

Answer
First, from the BATTER'S point of view:

It's EASIER to hit a LEFT-HAND pitcher if you're a right-hand batter.  And easier to hit a RIGHT-HAND pitcher if you're a left-hand batter.

That's because the ball's natural movement is TOWARD the batter, not away from him.

From the PITCHER'S point of view:

Right-hand pitchers should have greater success against right hand batters, because their ball is moving AWAY from a right hand batter.  And they'll have a harder time pitching to left-hand batters because their ball is coming TOWARD a left-hand batter.

Similarly, left-hand pitchers should do better against left-hand batters, and worse against right-hand batters.

That's why you'll see some managers send up a right-hand batter against a left-hand pitcher, and a left-hand batter against a right-hand pitcher.  He's just increasing the odds of the batter doing well.