The Building Blocks of Modern Baseball Analytics
Statcast, the high‑speed tracking system deployed at every major league ballpark, captures a treasure trove of data that goes far beyond simple box scores, giving analysts a granular view of every action on the field.
When a ball is struck with an exit velocity of 95 mph or more, Statcast tags it as a hard‑hit, a benchmark that correlates strongly with extra‑base hits and overall offensive production.
The system also records launch angle, and angles between eight and 32 degrees are considered the sweet spot for maximizing distance while keeping the ball in the air, a range that produces the most efficient fly balls.
From those two variables, analysts derive expected batting average, or xBA, which estimates the probability that a given batted ball will become a hit based on historical outcomes, offering a context‑rich alternative to traditional batting averages.
A related metric, expected weighted on‑base average (xwOBA), folds in exit velocity, launch angle and the runner’s sprint speed to produce a more nuanced view of a player’s offensive value, capturing the combined impact of skill and speed.
To smooth out outliers, Statcast calculates EV50, the average exit velocity of a batter’s hardest half of balls or a pitcher’s softest half, and Adjusted EV, which caps each reading at 88 mph before averaging, ensuring that extreme values do not skew the overall picture.
Bat speed, measured at the bat’s sweet spot, is another key indicator; a swing exceeding 75 mph is generally classified as fast, reflecting a more efficient transfer of energy from the hitter to the ball.
The vertical angle of the bat’s sweet spot at impact, often called attack angle, helps identify when a hitter is aiming for an Ideal Attack Angle of roughly 5‑20 degrees, a range that tends to produce line drives and consistent contact.
Swing steepness is gauged by the trajectory of the bat over the 40 ms before contact, giving scouts a sense of how steep or shallow a swing is and how it might affect launch characteristics.
Pitchers’ movements are broken down into inches of horizontal and vertical break, with the spin that drives that motion labeled Active Spin, while xERA translates xwOBA into a familiar ERA scale for easier comparison across pitchers.
Fielders benefit from metrics like Jump, which highlights those with the quickest reaction times and most direct routes, and Bolt, a sprint where a runner’s speed tops 30 ft/sec, underscoring elite baserunning and defensive agility.