extremely important. Let's say a closer is on 2-1 ball count with bases
loaded, and he pitches the fourth one laid in the corner of a strike zone.
When the umpire sees it as a strike, the ball count becomes 2-2, where the
pitcher leads the count, and batter is difficult to take his full swing due to
pressure of missing the ball. When the umpire calls it a ball, the ball
count becomes 3-1, where the batter leads the count, and the pitcher is
very difficult to throw any breaking balls out of the strike zone since one
more ball will allow a run.
A strike zone is an imaginary three dimensional figure, not a plane. And
according to the rules, the pitch should be called a strike even if the ball
makes a small contact with any part of the shape. Only if the ball passes
through the imaginary shape on the home plate, it is a strike whether the
ball is bounded, passed, hit a batter after it went through the zone. This
is why good breaking balls sinks near the home plate.
Image 3-16: Strike zone