Pitch Types Key
FA Fastball
FF 4-seam Fastball
FT 2-seam Fastball
FC Cut Fastball
FS Split-finger Fastball
FO Forkball
SI Sinker
SL Slider
CU Curveball
KC Knuckle Curve
EP Ephuus
CH Change-up
SC Screwball
KN Knuckleball
UN Unknown

Understanding the PITCHf/x Charts

Not sure what you're looking at? This page will teach you how to read the charts.

With all the different numbers and charts, it can be easy to lose track of what you're actually seeing. Each chart on this site is (or will be) summarized below.

Pitcher Charts

Pitch Virtualization Top

Pitch Virtualization Top

This chart is a horizontally compressed bird's eye view of the calculated average of each pitch in the data set.

The release point is calculated back to 55 feet from home plate. This is a decent but not always accurate approximation of a typical release point.

The ball's path is calculated by plugging the acceleration and velocity data provided by MLBAM into the standard equation for acceleration: x = ax0*t^2 + vx0*t + x0.

Pitch Virtualization Side

Pitch Virtualization Side

This chart is a horizontally compressed side view of the calculated average of each pitch in the data set.

The release point is calculated back to 55 feet from home plate. This is a decent but not always accurate approximation of a typical release point.

The ball's path is calculated by plugging the acceleration and velocity data provided by MLBAM into the standard equation for acceleration: z = az0*t^2 + vz0*t + z0.

Release Points

Release Points

This chart shows the vertical and horizontal position of the baseball in relation to the strikezone at 50 feet from home plate. The view is from the catcher's/batter's perspective.

At 50 feet from the plate, these positions reflect pitches that have already been released by the pitcher. For this reason, "release point" is not an entirely accurate name for this chart.

Velocity vs Spin Angle

Velocity vs Spin Angle

This chart plots pitch velocity against the direction in which the pitch is spinning.

This chart is a useful tool to help determine the accuracy of pitch type identification for the selected data.

"Spin Angle" was not added to the data set published by MLBAM until 2009, so this chart will not show any pitches from 2008.

Spin Movement

Spin Movement

This chart represents gravity-neutral pitch movement caused by the spin of the baseball.

Positive vertical values represent pitches that resisted gravity. Negative vertical values represent pitches that dropped faster than gravity.

Movement is charted from the catcher's/batter's perspective.

Spin Movement w/Gravity

Spin Movement w/Gravity

This chart adds the effect of gravity to the Spin Movement chart. It is necessary to help represent the true movement of pitch. Slow pitches are more affected by gravity because they are in the air for a longer period of time.

The calculated effect of gravity is from 40 feet to the front edge of the plate. When I find the link to the correct explanation for this, I will provide it.

Pitch Locations

Pitch Locations

This chart shows the locations of pitches as they crossed the plate. View is from the catcher's/batter's perspective.

Pitch heights are normalized to the PITCHf/x operator's selected strikezone heights. For each batter, a human operator sets the top and bottom of the strike zone. There is room for error, but this method puts the strikezone of a tall batter in perspective with that of a short batter.

Called Strike Zone

Called Strike Zone

This chart shows the locations of pitches as they crossed the plate as balls or strikes. View is from the catcher's/batter's perspective.

This chart only shows balls and strikes as called by an umpire. By its nature, this chart only shows pitches at which the batter did not swing.

Pitch heights are normalized to the PITCHf/x operator's selected strikezone heights. For each batter, a human operator sets the top and bottom of the strike zone. There is room for error, but this method puts the strikezone of a tall batter in perspective with that of a short batter.



Batter Charts

Spray Chart

Spray Chart

This chart shows batted ball locations overlaid on a diagram of the batter's home ballpark.

This chart is not normalized. Dimensions and locations of field landmarks (home plate, foul lines, etc.) vary from park to park. Because of this, batted ball locations from other ballparks do not map perfectly.

Swing Pitch Types

Swing Pitch Types

This chart shows the locations of pitches as they crossed the plate. View is from the catcher's/batter's perspective.

This chart only shows pitches swung at by the batter.

Pitch heights are normalized to the PITCHf/x operator's selected strikezone heights. For each batter, a human operator sets the top and bottom of the strike zone. There is room for error, but this method puts the strikezone of a tall batter in perspective with that of a short batter.

Take Pitch Types

Take Pitch Types

This chart shows the locations of pitches as they crossed the plate. View is from the catcher's/batter's perspective.

This chart only shows pitches taken by the batter.

Pitch heights are normalized to the PITCHf/x operator's selected strikezone heights. For each batter, a human operator sets the top and bottom of the strike zone. There is room for error, but this method puts the strikezone of a tall batter in perspective with that of a short batter.

Called Strike Zone

Called Strikezone

This chart shows the locations of pitches as they crossed the plate as balls or strikes. View is from the catcher's/batter's perspective.

This chart only shows balls and strikes as called by an umpire. By its nature, this chart only shows pitches at which the batter did not swing.

Pitch heights are normalized to the PITCHf/x operator's selected strikezone heights. For each batter, a human operator sets the top and bottom of the strike zone. There is room for error, but this method puts the strikezone of a tall batter in perspective with that of a short batter.