UZR

UZR, or Ultimate Zone Rating, is a baseball defensive metric designed to estimate a fielder’s value by measuring runs saved above or below an average defender. The statistic is zone-based, dividing the field into regions and evaluating how often a fielder makes plays on balls in those zones relative to an average defender. A player with a positive UZR has saved runs compared to an average fielder, while a negative UZR indicates more runs allowed.

Methodology in broad terms involves using ball-in-play data to assign each batted ball to a fielder and to estimate the probability of making the play if an average defender were in position. The outcomes are then aggregated across a player’s fielding opportunities and expressed as runs saved per season, often scaled to a 150‑game basis (UZR/150). UZR aims to capture a fielder’s range, the ability to get to balls, and sometimes throwing or fielding efficiency, though the exact components can vary by implementation.

UZR is widely used in baseball analytics to evaluate and compare defensive performance, informing player development, roster decisions, and contract discussions. It has been embraced by major analytics outlets and is frequently cited alongside other defensive metrics like Defensive Runs Saved (DRS). Limitations include sensitivity to sample size, data quality, and park or era effects, as well as methodological differences between implementations, which can lead to discrepancies with other metrics.