Deciphering Defense

Most peoples opinion of defense have one fatal flaw… It’s their opinion. Most stats are inconclusive and can be spun to the arguers opinion. While most stats on defense are inconclusive, there are some key stats to look for to get a better understanding of ability.

The first such stat is RZR. The Fangraphs Sabermetric Library states: Revised Zone Rating (RZR) measures, “the proportion of balls hit into a fielder’s zone that he successfully converted into an out” (Hardball Times). Invented by John Dewan and displayed on the Hardball Times for a number of years, it has fallen out of fashion over the years as more advanced, accurate measures have become available (like UZR and DRS), but it still works as an introductory defensive statistic to show saber-newbies how advanced defensive statistics work.

There are a few words in there that give me hesitance. But the key is, “the proportion of balls hit into a fielder’s zone that he successfully converted into an out”. So, actually this is a combination of two numbers on the fangraphs leaderboard. BIZ and PLAYS. BIZ is simply “balls in play”. And PLAYS is the number of plays made out of the BIZ zone. RZR is the percentage of those plays made. Lets look at the Dodgers abilities according to RZR.

This isn’t yet a full study of defensive ability. But it is pretty straight forward. Did you catch the ball that was hit in your zone? Lets add one more variable to this.

OOZ. The magical world of … outs. Specifically, outs made outside of BIZ. Sometimes, there are plays you should get to and that is RZR. But, sometimes there are plays that are outside of your zone that you have no business making. These plays are considered outside of your zone (OOZ).

I figure this is a comprehensive equivalent for range. These are generally the first two stats I look at when trying to figure out what kind of defensive player we have on our hands. Lastly, lets take a look at UZR…

It’s a bit of a doozy. UZR stands for Ultimate Zone Rating. It combines 4 different numbers into a “runs saved” equation. The problem with UZR is, it requires a large sample size to get a good understanding of true ability. Lets pretend that the field is divided into multiple zones (more than the 9 that we have already divided it into). In fact, lets divide the field into 64 separate zones.

Example: A ball normally hit into zone 47 usually adds .224 runs. Therefore, if the fielder made an out of that specific ball hit to zone 47 he saved .224 runs. The numbers can be taken from 4 (previously mentioned) stats: outfield arm ability, double play ability, range ability, and errors saved. Simply put, what is the difference in plays that Player “A” makes versus the league average. Fangraphs then takes it a step further by adding UZR/150. It projects what your UZR would be over 150 games played supposing that you made the same plays that had made if you played 150 games.

The numbers for the Dodgers players aren’t too different from what we might have gathered from RZR and OOZ. There isn’t any perfect way to figure out how good a player is with the glove. But hopefully, something like this will go a long way in determining how good the Dodgers as a team are with the glove, better than average.