Ultimate Zone Rating (UZR) is a defensive fielding metric that measures the number of runs a player saves or costs his team compared to the average fielder at his position.
A player with a 0.0 UZR is an average fielder, so a positive UZR indicates an above-average fielder and a negative UZR indicates a below-average fielder.
While UZR is thought to be accurate, it is wise to compare its ratings with those of other fielding statistics, your own eyes, and the Fans Scouting Report. Fans Scouting Report is converted to UZR format and can be used interchangeably if FSR appears to be more accurate.
Like all stats, UZR has its flaws, and one is that it tends to fluctuate from season to season, which is why it’s best to look at a player’s last three seasons of fielding data, rather than just their most recent season.
UZR is derived by dividing the baseball field into 64 zones and calculating the percentage of balls hit into each zone that a player converts into outs. Infield line drives, foul balls, and infield popups are excluded from the data.