Statcast: Glossary of terms

Statcast™, MLB's state-of-the-art tracking technology, is now available in every Major League ballpark.

As fans become accustomed to seeing Statcast™ used on a nightly basis, they will also start seeing terminology associated with it. Here's a breakdown of what those terms mean.

PITCHING

Release: Measures the time from pitcher's first movement out of the stretch to the release point of the pitch.

Extension: Measures the distance of the release point of the pitch from the front edge of the pitching rubber.

Velocity: Measures the peak velocity of a pitch at any point from its release to the front edge of home plate.

Perceived velocity: Velocity of the pitch at the release point normalized to the average release point for MLB pitchers. For example, a 90-mph pitch at a 54-inch release point will seem faster to the batter than a pitch of the same velocity thrown from a 56-inch release point.

Spin rate: Measures the spin rate of the ball at the point of the release from the pitcher's hand.

HITTING

Exit velocity: Velocity of the ball off the bat on batted balls.

Launch angle: The vertical angle at which the ball leaves the bat on a batted ball.

Vector: Classifies the horizontal launch direction of the batted ball into five equal zones of 18 degrees each.

Hang time: Measures the time from bat contact to the ball either hitting the ground/wall or contact by a fielder.

Hit distance: Calculates the distance on the ground of the actual landing point of any ball hit into play, ground/wall or contact with fielder, regardless of outcome.

Projected HR distance: Calculates the distance of projected landing point at ground level on over-the-fence home runs.

BASERUNNING

Lead distance: Measures the distance between the base and the runner's center of mass at the time the pitcher goes into his windup on a pitch or pickoff attempt.

Secondary lead: Measures the distance between the base and the runner's center of mass when the ball is released by the pitcher on a pitch or pickoff attempt.

First step: Measures the time elapsed from time of bat-on-ball contact to the runner's first movement toward next base.

Stealing first step: Measures the time elapsed from the pitcher's first movement in the stretch to the runner's first movement toward the next base on a steal attempt.

Acceleration: Measures the time elapsed from time of bat-on-ball contact to the runner's max speed at any point ball is in play.

Max speed: Measures the maximum speed at any point for all players while the ball is in play.

Dig speed: Measures the time from bat-on-ball contact to the point where the batter-as-runner reaches first base on an infield ground ball.

Extra bases: Measures the time of bat-on-ball contact to the point the runner advances an "extra" base (first to third or home, or second to home) on all hits (excluding over-the-fence home runs).

Home run trot: Measures the time elapsed from time of bat-on-ball contact to the point where the batter-as-runner reaches home plate on home runs.

FIELDING

First step: Measure the time elapsed from time of bat-on-ball contact to the fielder's first movement toward the ball.

First step efficiency: Measures the angle of deviation from a straight line to the ending point of a batted ball trajectory vs. the actual initial path taken toward the ball.

Max speed: Measures the maximum speed at any point while tracking any ball hit into play.

Acceleration (outfield): Measures the time elapsed from time of bat-on-ball contact to max speed at any point while pursuing any ball hit into the outfield.

Total distance: The total distance covered from batted ball contact to fielding the ball.

Arm strength: Measures the maximum velocity of any throw made by any fielder.

Exchange: Measures the time from the point a fielder receives the ball to releasing a throw.

Pop time: Measures the time elapsed from a pitch reaching catcher's glove, to throw, to receipt of the ball by fielder at the intended base on all pickoff throws and steal attempts.

Pivot: Measures the time elapsed between receipt of the ball and release of throw on double-play attempts.

Route efficiency (outfield): Divide the distance covered by the fielder by a straight-line distance between the player's position at batted ball contact and where the ball was fielded.