Glossary

With the vast amount of information that is available to analyze every single pitch in today’s game, it can be overwhelming just trying to decide where to start. When looking at exit velocity numbers or metrics regarding a pitcher’s release point, baseball can quickly go from being the best sport in the world to looking more like a math test that even the teacher doesn’t know the answers to. Let this page serve as a guide to make sense of any and every meaningful data point and metric that can be valuable to players and teams alike. Click the links for a more in-depth look at each metric.

Hitting

• Exit Velocity: The speed of the ball when it initially comes off the bat, measured in MPH.
• Launch Angle: The vertical angle of the ball when it initially comes off the bat. A positive number means the ball is initially traveling upward while a negative number means it is initially traveling downward.
• Z-Swing%: The percentage of the time that a batter swings at a pitch inside of the strike zone.
• O-Swing%: The percentage of the time that a batter swings at a pitch outside of the strike zone.
• SwStr%: The percentage of the time that a batter swings and misses.
• wOBA: A ‘catch-all’ batting metric that measures a batter’s at-bats based on their value in terms of run creation.
• xwOBA: xwOBA analyzes the exit velocity and launch angle of every batted ball from a hitter. From there, a probability of the outcome of the batted ball is determined. This creates a metric that shows what a hitter’s wOBA should be.

Pitching

• Spin Rate: The speed at which the ball is spinning when it initially leaves the pitcher’s hand. Measured in revolutions per minute (RPM).
• Release Height: The height above home plate that the pitcher releases the ball at. This data point is collected by FlightScope and Trackman machines alike and, when combined with the metric ‘Release Side’, can be used to create visuals to display a pitcher’s release point on any pitch.
• Release Side: Distance from the center of the pitching rubber at which the pitcher releases the ball. Balls thrown from the right side of the mound from the pitcher’s perspective will have a positive number, and balls thrown from the left side of the mound from the pitcher’s perspective have a negative number. This data point is collected by FlightScope and Trackman machines alike and, when combined with the metric ‘Release Height’, can be used to create visuals to display a pitcher’s release point on any pitch.
• Release Extension: The horizontal distance from the pitching rubber to the point where the pitcher releases the ball.
• ERA: The most popular metric used to measure a pitcher’s performance, ERA shows the number of earned runs a pitcher allows per 9 innings. Measured by (Earned Runs*9/Innings Pitched).
• FIP: An advanced pitching metric that projects what a pitcher’s ERA should be based on plays that are not affected by the defense.