Advanced Stats 201: UZR

In the statistical world of baseball, one of the most argued categories is defense. How do we measure it? How can we measure it? Are the stats accurate? When I see Brendan Ryan make a play up the middle at shortstop, and then Elvis Andrus make a play on the same ball, how do we differentiate between the two?

All of these questions have been asked time and time again, over and over. So what the Sabermetricians and other “stat-heads” have done is to create defensive stats. Before we go any further, there is a lot of contention about how much weight these defensive stats hold, and how accurate the really are. While defensive stats are great to help us realize range, hands, arm strength and other attributes of a player, they are not 100% accepted. There are proponents who say that after three years, UZR and others are an accurate way to measure defensive, and opponents who say that the positioning of a player on a certain play, plays a factor and that’s not figured in. We aren’t here to gauge whether UZR is accurate or not, that is up to you. What we will attempt to do, is breakdown what it is about, and how it factors into the everyday grind of baseball.

UZR (Ultimate Zone Rating) is the most widely used defensive stat available to us as the public. UZR uses several different components to come to a conclusion about a player’s defensive prowess. They include:

  • Outfield Arm Runs (ARM) – The amount of runs above average an outfielder saves with their arm by preventing runners to advance.
  • Double-Play Runs (DPR) – The amount of runs above average an infielder is in turning double-plays.
  • Range Runs  (RngR) – Is the player an Ozzie Smith or an Adam Dunn? Do they get to more balls than average or not?
  • Error Runs (ErrR) – Does the player commit more or fewer errors compared with a league-average player at their position?

Calculating UZR is rather difficult, so we won’t go that far today. Basically UZR just tells us how good a defender is, compared to the league average. UZR breaks the field down into 78 “zones”, 64 of which are used top calculate the stat. Confused yet? Lets simplify it. The following is a chart of how to measure UZR from player to player: 

. Defensive Ability UZR
. Gold Glove Caliber 15
. Great 10
. Above Average 5
. Average 0
. Below Average -5
. Poor -10
. Awful -15
To give us an idea of how good or how bad players can be, we’ll use the 2012 Texas Rangers, since most readers here watch that team more than others. Gentry and Beltre were the best on the team with UZR’s of 13.7 for Gentry and 10.7 for Beltre. the two worst were Michael Young at -4.8 and shockingly Josh Hamilton at -12.6.
Hopefully we’ve given you a basic understanding of UZR without confusing you too much. Again, when looking at UZR beware of sample sizes. the above paragraph is only for 2012, so the terrible rating for Hamilton may not be a true measure. We simply used it to show you differences in ratings. Happy SABRing!
Patrick Despain is the CEO and Co-Founder of ShutDown Inning. He can be reached or on Twitter @ShutDownInning
Patrick Despain
Patrick is a member of the IBWAA and creator of Shutdown Inning. He was raised him Arlington, Texas and grew up watching games on HSE and listening to Eric Nadel and Mark Holtz on the radio. He is a long time Rangers fan and never achieved his dream of being a bat boy. He know lives in Georgia with dreams of a Texas return.

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