Statcast | Glossary | MLB.com (2024)

About Statcast

Statcast is a state-of-the-art tracking technology that allows for the collection and analysis of a massive amount of baseball data, in ways that were never possible in the past. Statcast can be considered the next step in the evolution of how we consume and think about the sport of baseball, encompassing pitch tracking, hit tracking, player tracking and even bat tracking for all Major League games.

The foundations of MLB tracking data were laid in 2008, when Major League Baseball first installed pitch tracking hardware in every Major League stadium. That step unlocked a new age of baseball fandom, and Statcast builds upon that innovation by measuring everything the previous system did, along with a great deal more. Statcast was installed in all 30 MLB ballparks in 2015 after a partial trial run in 2014.

From 2015-19, Statcast consisted of a combination of camera and radar systems. That changed in 2020, with the arrival of Hawk-Eye. A high-speed camera system previously known for powering the instant replay system in professional tennis, among other things, Hawk-Eye offers increased tracking ability as well as a host of exciting new features, such as better biomechanical tracking of players and, as of 2024, bat tracking data like hitters' swing speeds and swing paths.

Each club now has 12 Hawk-Eye cameras arrayed around its ballpark. Five of those are high-frame-rate cameras -- which were upgraded from 100 frames per second to 300 fps in 2023 -- that focus on bat tracking and pitch tracking. The other seven are dedicated to tracking players and batted balls. This more robust system has raised the percentage of batted balls that get tracked from roughly 89% to 99%.

Statcast is tracking and quantifying much of the action on the field. That applies to pitching (velocity, spin rate and spin direction, pitch movement), hitting (exit velocity, launch angle, batted ball distance), running (sprint speed, base-to-base times) and fielding (arm strength, catch probability, catcher pop time). While those numbers are collected on a play-by-play level, they also become the basis for stats that measure players across seasons, such as hard-hit rate for batters or Outs Above Average for fielders.

These metrics allow front offices, broadcasters and fans alike to quantify the raw skills of players in ways that were previously available only to scouts or not available at all. In the 2023 season, from Opening Day through the end of the World Series, more than 725,000 pitches and more than 125,000 batted balls were tracked by Statcast. Meanwhile, terms such as "exit velocity," "launch angle" and "spin rate" have become ubiquitous not just on broadcasts, but also on ballpark video boards and even on the field, as players across the Major Leagues use the data and the thinking behind it to elevate their games.

Available Data

Statcast currently reports measurements (raw numbers from the on-field action) and metrics (combinations of raw measurements into useful numbers).

Measurements include:

Arm Strength: How hard, in miles per hour, a fielder throws the ball.

• Bat Speed: How fast the sweet spot of the bat is moving, in mph, at the point of contact with the ball (or where the ball and bat would have met, in case of a swing-and-miss).

Extension: How far in front of the pitching rubber, in feet, a pitcher releases the pitch.

Exit Velocity: How hard, in miles per hour, a ball was hit by a batter.

Launch Angle: How high, in degrees, a ball was hit by a batter.

Pitch Velocity: How fast, in miles per hour, a pitch is thrown.

Pop Time: How quickly, in seconds, a catcher can get the ball out of his glove and complete his throw to a base on a stolen-base or pickoff attempt.

Spin Rate: How much spin, in revolutions per minute, a pitch was released with.

Metrics include:

Barrels: A batted ball with the perfect combination of exit velocity and launch angle, or the most high-value batted balls. (A barrel has a minimum Expected Batting Average of .500 and Expected Slugging Percentage of 1.500.)

Blasts: A new Statcast metric using bat tracking data, blasts are batted balls that combine a fast swing speed and squared-up contact on the sweet spot of the bat. A blast is the most valuable type of swing because it meshes bat speed with efficient contact. The strict definition of a blast is "percent squared up*100 + bat speed >= 164." For example, a swing where the hitter has an 80 mph bat speed and makes 90% squared-up contact would qualify as a blast because the sum of those two numbers is 170.

Catch Probability: The likelihood, in percent, that an outfielder will be able to make a catch on an individual batted ball. Catch Probability accounts for the fielder's distance needed, time available to make the catch, direction and proximity to the wall, and compares each play to how often the same opportunity is caught by Major League outfielders. This allows Statcast to get past the eye test and say "that ball gets caught 25% of the time," for example.

Expected Batting Average (xBA): xBA measures the likelihood that a batted ball will become a hit. Each batted ball is assigned an xBA based on how often comparable balls -- in terms of exit velocity, launch angle and, on certain types of batted balls, Sprint Speed -- have become hits since Statcast was implemented Major League-wide in 2015. For example, Ronald Acuña Jr. led qualifying MLB hitters with a .357 xBA in 2023 (even higher than his .337 actual batting average), followed by Luis Arraez with a .329 xBA and Freddie Freeman with a .323 xBA.

Expected Weighted On-base Average (xwOBA): xwOBA is formulated using exit velocity, launch angle and, on certain types of batted balls, Sprint Speed. In the same way that each batted ball is assigned an xBA, every batted ball is given a single, double, triple and home run probability based on the results of comparable batted balls since Statcast was implemented Major League wide in 2015. xwOBA also factors in real-world walk and strikeout numbers, and is reported on the wOBA scale. By comparing expected numbers to actual outcomes over a period of time, it can be possible to identify which hitters (or pitchers) are over- or underperforming their demonstrated skill.

Outs Above Average (OAA): A range-based metric of defensive skill that shows how many outs a fielder has saved over his peers. Prior to 2020, OAA was an outfield-only metric. But it has since been expanded to include infielders. OAA is calculated differently for outfielders and infielders.

Sprint Speed: A measurement of a player's top running speed, expressed in "feet per second in a player's fastest one-second window." This can be delivered on individual plays or as a season average, found by taking all qualified runs (currently defined as anything two bases or more, excluding homers, plus home-to-first runs on "topped" or "weakly hit" ground balls) and averaging the top half of those. In 2023, Elly De La Cruz and Bobby Witt Jr. tied for the Major League lead with a 30.5 ft/sec Sprint Speed, while the MLB average is 27 ft/sec.

Baseball Savant

BaseballSavant.MLB.com is MLB.com's clearinghouse for Statcast data. That includes the Savant Illustrator tool for making custom graphics, pre-made leaderboards for top-level metrics like Barrels, Sprint Speed, Outs Above Average and Pop Time, as well as a powerful Search tool that allows users to create their own custom queries.

For example, a user could seek to find which batters hit the most opposite-field home runs in 2023. (The answer is Julio Rodríguez, with 12). They could look to see how the frequency of MLB teams employing infield shifts changed from 2015 to 2022, the final season before MLB's rule changes limited the shift. And they could wonder which pitchers got the most swinging strikes on four-seam fastballs thrown in the strike zone and find that in 2023 it was Spencer Strider, with 208. There's a nearly endless combination of questions that can be answered using Baseball Savant's public-facing search tool.

In addition, Baseball Savant provides a real-time Gamefeed for any game played in a Statcast-enabled ballpark, and offers an interactive 3D pitch-tracking system.

Below is a full glossary of Statcast terms:

Statcast | Glossary | MLB.com (2024)

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