UZR - Ultimate Zone Rating

[Colby]

UZR - Ultimate Zone Rating
One of the best defensive sabermetrics, UZR is tough to understand intuitively.  All you need to know is that UZR puts a run value to defense, attempting to quantify how many runs a fielder saved or gave up through errors or bad plays. 

There are a couple different components to UZR including:

• 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) – Does the player get to more balls than average or not?
• Error Runs (ErrR) – does the player commit less or more errors compared with a league-average player at the position?

These categories are then all compiled into a combined sabermetric, UZR.  Since UZR is measured as runs, it can be compared easily with a player’s offensive contributions (wRAA or RC).

Since UZR is a counting statistic like hits or runs created, the more playing time you have the higher (or lower) your will be.  In order to compare players with different amounts of playing time, UZR may be scaled on a 150 game basis ().  UZR is park-adjusted, meaning it adjusts for the fact that some left fielders play primarily in hitter-friendly Yankee Stadium while some play in Safeco Field.