Horizontal and Vertical Pitch Movement

[SteveA]

I went to a couple games at PNC Park last weekend.

After each pitch, the scoreboard shows the speed of the pitch, and also shows the horizontal and vertical movement in inches. The vertical has a + or - sign, can't remember if the horizontal does too.

What exactly do those numbers mean and what info can be gleaned from them?

The vertical component can't just be measuring the change in elevation from where the pitcher releases it to where it ends up. Because there were plenty of pitches with + vertical movement and obviously if a 6'4" overhand pitcher standing on mound releases the ball, if it had + vertical movement it would literally be 3 feet over the hitter's head.

So what do those #s represent exactly? Some type of deviation from an "expected" path?

Inquiring minds want to know....

[Stotle]

Vertical is relative to where the ball would be expected to go with no force on it other than gravity. So, a + vert shows inches above where the ball would generally be expected to hit.