What is UZR? Definition, Formula, and Example
UZR (Ultimate Zone Rating) measures a fielder's total defensive value in runs above or below an average player at the same position, combining range, errors, double plays, and outfield arm strength.
What is UZR in baseball?
Ultimate Zone Rating (UZR) is a defensive metric that estimates how many runs a fielder saves or costs his team compared to a league-average player at the same position. UZR is expressed in runs: +10 means the player saved roughly ten more runs than an average fielder over the same number of innings; -10 means he cost his team ten runs. It is the longest-running advanced defensive stat in mainstream use, popularized by FanGraphs, and along with DRS forms the backbone of the defensive component in WAR.
How UZR is calculated
UZR slices defense into four components, each measured in runs:
- Range Runs (RngR) — credit for converting balls hit into a fielder's zone into outs, weighted by how often each batted-ball type is fielded by the average player at that position.
- Error Runs (ErrR) — runs lost to errors compared to the positional average.
- Double Play Runs (DPR) — infielders only; credit for turning double plays in DP opportunities.
- Outfield Arm Runs (ARM) — outfielders only; credit for preventing baserunner advancement and recording assists.
The formula is essentially:
UZR = RngR + ErrR + DPR + ARM (infield uses RngR + ErrR + DPR; outfield uses RngR + ErrR + ARM)
UZR is then often shown as UZR/150 — UZR scaled to 150 defensive games — for comparison across players with different playing time. The benchmarks are roughly: +15 elite (Gold Glove), +10 great, +5 above average, 0 average, -5 below average, -10 or worse poor.
Worked example
Nolan Arenado's defense at third base has consistently graded as elite by UZR. In his 2022 season with the Cardinals he posted roughly +10.7 UZR in about 1,300 innings at third — meaning he saved his team about 11 runs versus an average third baseman. Range Runs drove the bulk of that figure, reflecting the unusually large number of balls he converted into outs in the 5–6 hole, and his Error Runs were also positive thanks to a sub-average error rate on routine plays. Compare that to Rougned Odor's late-career second-base seasons, where UZR ran in the -8 to -10 range — same scale, opposite story.
Why UZR matters
Front offices use UZR to put a run value on a glove the same way wOBA puts one on a bat. A +10-UZR shortstop is worth roughly one extra win per season on defense alone, so UZR feeds directly into WAR and into contract valuation. Fantasy managers care less about UZR directly, but it predicts playing time: a -10 UZR corner outfielder gets benched against tough lefties or pulled for a defensive replacement late.
Limitations and common misconceptions
UZR is noisy in single-season samples. A typical 1,200-inning season has a standard error of roughly ±5 runs, which means a +6 UZR season and a 0 UZR season are statistically indistinguishable. Defensive analysts recommend looking at three-year UZR before drawing conclusions about a fielder's true talent. UZR also does not include catcher framing — catcher UZR isn't published, because pitch-receiving and game-calling drive far more value than range. Finally, UZR is a zone-based metric built on stringer-classified batted balls; Statcast-era OAA, which uses tracking data, has largely replaced UZR for outfielders in modern evaluation.
Related terms
In Legends Deck
Legends Deck blends UZR, DRS, and OAA into a single defensive rating per position on every fielder card, so when you slot Arenado at third in your lineup his glove changes ground-ball outcomes the same way his bat changes plate appearances. UZR's three-year stabilization curve is why our defensive ratings weight multi-season totals rather than a single hot or cold year.