Introduced before the 2017 season, Hit Probability is a Statcast metric that measures the likelihood that a batted ball will become a hit.
Using exit velocity and launch angle, each batted ball is assigned a percentage based on how often comparable balls have become hits since Statcast was implemented Major League wide in 2015. For instance, a batted ball with a Hit Probability of 70 percent is given that figure because balls with a similar exit velocity and launch angle have become hits seven out of 10 times.
Barreled Balls -- a metric introduced in 2016 -- have a combination of exit velocity and launch angle that results in a minimum Hit Probability of 50 percent, though the Hit Probability of the average Barreled Ball is much higher (82 percent).
Why it's useful
Hit Probability tries to get to the heart of what a pitcher and hitter control while attempting to take out the effects of defense and ballpark. Setting aside foot speed for infield hits, a batter's impact on whether the ball was a hit or an out ends as soon as the bat makes contact. Likewise, a pitcher cannot control what happens to a batted ball after it leaves the bat.
With knowledge of the probable outcome of each batted ball, an expected OPS can be created for each player -- factoring in the run value of every batted-ball type as well as non-contact figures like a player's strikeout and walk rates.
Watch: Statcast measures the Hit Probability on several batted balls.