The New Language of Baseball
Baseball Savant has become the backbone of modern baseball analysis, offering a treasure trove of data that goes far beyond traditional stats.
At the heart of its system is the definition of a hard‑hit ball: any batted ball that leaves the bat at 95 mph or faster, a threshold that separates casual contact from genuine power.
From that simple benchmark, Savant builds metrics such as xBA, which estimates the probability that a given batted ball will become a hit by factoring in exit velocity and launch angle, and xwOBA, which adds sprint speed into the equation to capture the full quality of a hit.
Batters are evaluated with EV50, the average exit velocity of their hardest half of swings, while pitchers are judged by the EV50 of the softest half of balls they allow, highlighting the opposite ends of the spectrum.
Adding another layer, Adjusted EV caps the maximum exit velocity at 88 mph for analytical consistency, and it is paired with bat speed measurements taken at the sweet spot, where the top 90 % of swings are used to calculate an average speed.
A fast swing is flagged when bat speed reaches 75 mph or more, and the trajectory of a well‑struck ball is considered ideal when its launch angle falls between five and twenty degrees, producing the most efficient path toward a hit.
Pitchers' movements are quantified in inches, comparing each pitch's actual break to the league average, while active spin measures the portion of spin that directly contributes to that movement, expressed in revolutions per minute.
Defensive Impact and Running Speed
On the bases, top running speed is captured during a one‑second burst, and a Bolt is defined as any sprint that hits or exceeds 30 ft/sec, a benchmark that highlights elite acceleration.
Defensive metrics such as Jump evaluate outfielders' reaction speed and direct routes, while out‑saving ability quantifies how many outs a player prevents compared to peers, and xERA translates xwOBA into a more digestible ERA‑like figure for pitchers.