In baseball, fans see many kinds of defensive shifts. Let’s focus on the standard infield shift. Major League Baseball defines an official shift as having at least three of the four infielders positioned on one side of second base at the time of the shift.
Why shift? The answer is simple.
“The rationale for the shift is pretty intuitive: Both left-handed and right-handed hitters tend to pull about three-quarters of their ground balls, so it seems smart to position more fielders where the ball is likely to go. Shifts against lefties have been proved to prevent hits on the whole…” — Ben Lindbergh