Baseball Glossary › Ultimate Zone Rating
Ultimate Zone Rating (UZR)
Ultimate Zone Rating (UZR) estimates how many runs a fielder saved or cost his team compared with an average defender at the same position. It accounts for range, errors, outfield arm and double-play ability, using batted-ball location data. Zero is average, positive numbers are above average and negative numbers are below average.
What to Know
UZR charts where each ball is hit and how often similar balls are turned into outs. If similar fly balls are caught 60 percent of the time, a fielder who catches one gains credit for the difficulty and a fielder who misses one loses credit. The total is compared with league average and converted into runs.
FanGraphs offers a rule-of-thumb scale for a full season: about +15 is Gold Glove caliber, +10 great, +5 above average, 0 average, -5 below average, -10 poor and -15 awful. FanGraphs also stresses that defensive stats need big samples and recommends about three years of UZR data before drawing firm conclusions.
UZR vs DRS: Defensive Runs Saved uses the same concept with a slightly different formula, so the two usually agree. Statcast's Outs Above Average measures in outs rather than runs. All three improve on fielding percentage, which only counts errors.
Frequently Asked Questions
What is UZR in baseball?
UZR stands for Ultimate Zone Rating. It estimates how many runs a fielder saved or cost his team compared with an average defender at his position, combining range, errors, arm and double-play ability.
What is a good UZR?
FanGraphs' rule-of-thumb scale for a full season puts about +15 at Gold Glove caliber, +10 great, +5 above average and 0 average. Negative numbers are below average, with -15 considered awful.
What is the difference between UZR and DRS?
They share the same concept: converting a fielder's plays made and missed into runs above or below average. The formulas differ slightly, so they sometimes disagree on a player, but FanGraphs notes they agree more often than they disagree.
How many games do you need for UZR to be reliable?
A lot. FanGraphs warns that UZR does not work well in small samples and recommends using about three years of data before judging a fielder's true talent level.
What is UZR/150?
UZR/150 scales a player's UZR to a 150-game basis. Because UZR is a counting stat, this lets you compare a player who played 90 games with one who played 140.
Is UZR used for catchers?
No. FanGraphs notes there is no UZR data for catchers, so catcher defense in its WAR uses other measures, such as stolen-base runs saved and runs saved on passed pitches.
Related Terms
Sources
- MLB.com Glossary: Ultimate Zone Rating (UZR)
- FanGraphs Sabermetrics Library: UZR
- FanGraphs Sabermetrics Library: What is WAR?
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