What is changeup in baseball?
A changeup in baseball is a type of pitch thrown by the pitcher that is different in speed, often slower than the previous pitch but has the appearance and path of a fastball, deceiving the hitter and causing him to mistime his swing.
With a changeup pitchers change the pace of a pitch. A pitch does not have to only change directions in order to deceive batters. Differing or slow velocities can also be used to make pitches harder to hit; these types of pitches are called off-speed pitches. Changeups are a common type of off-speed pitch. They look very similar to a fastball -- they are thrown in a similar way and have a straight path -- but are significantly slower than a fastball. While fastballs are usually 90 MPH or above, changeups are usually only 70-80 MPH. For batters, it is often difficult to detect the difference between a fastball and a changeup, since they have the same path and the speed of the baseball cannot be determined until it is very close to the batter. That is why changeups are so effective: They trick batters into thinking the pitch is a fastball, and the batter will swing at it. However, since changeups are much slower than fastballs, the swing would be too early, either missing the baseball completely or hitting it weakly.