This is a baseball term which refers to a pitching style in which a pitcher attempts to decrease the reaction time of a hitter by throwing very fast, or creating the illusion of throwing fast. This style is well suited to pitchers with a very accurate, high speed fastball. The pitcher will consistently throw fastballs in an attempt to decrease the time between the ball leaving his/her hand, and the ball reaching home plate. The less time the ball spends in the air, the less time a batter has to react and swing. Another way to describe this style is a pitcher pitching faster than the batter's bat speed. Even if a batter makes the quick decision to swing, he/she must still get the bat around fast enough to make contact with the ball.
Two of the most famous pitchers who effectively used this technique are Nolan Ryan and Randy Johnson. The former is famous for his fastball and his record seven (7) no-hitters (a no-hitter is when pitcher does not give up a single hit the entire game); the latter is famous for his long arms and speedy fastball. A pitcher who chooses to use this style must also throw other types of pitches in order to keep the batter guessing. There are many fastball pitchers who also use the curveball and change-up effectively to alter the path or speed of the ball respectively, while keeping the wind-up and delivery of a fastball.