Defensive Statistics

What defensive statistics are on the internet and available to a baseball fan?

By Makakilo Nov 2, 2020, 8:00pm EST

Don’t doubt the baseball gods. They described defense with high tech data and calculations seemingly beyond mortal understanding. Not just once. They did it a half-dozen times, each statistic different than the others. Each time a new acronym was born – DRS, FRAA, OAA, Rtot/TZTFR, UZR, and SDI (which combines TZ, DRS, RED, UZR, and DRA). Which statistic is best depends on the answer you seek.

Before we proceed, ‘easy’ is an option. Each team has an average runs allowed per game. No adjustments are required to compare teams. Nevertheless, you could consider the strength of each team’s pitching, and the offensive strength of the opponents faced.

Let’s look at some defensive statistics that were found on-line by a Diamondbacks’ baseball fan (me).

Fielding Runs Above Average (FRAA) is at Baseball Prospectus.

(FRAA) relies on putouts, assists, and situational adjustments. It ignores fielder position and batted ball data. The most recent chart that I found was for 2019. It included 63 players. Kole Calhoun was number 6. A snip of the screen follows:

Outs Above Average (OAA) is at Baseball Savant.

OAA measures the likelihood of catching the ball based on, “How far did the fielder have to run?”, and, “How much time did he have to get to the ball?” There is a leaderboard, and you can look at Diamondbacks with at least 10 fielding attempts. In addition to OAA, it provides other information, such as success rate & estimated success rate for catch attempts.

In 2020 Nick Ahmed and Tim Locastro had the highest OAAs. A snip of the screen follows.

For outfielders, Statcast data is provided at Baseball Savant.

After balls-in-play are grouped into ‘bins’ based on how difficult they are to successfully field, Statcast displays outs vs. opportunities for each bin. The easiest 5% of balls-in-play are not shown in the chart. Here is a link to the catch leaderboard. A snip of the screen follows:

If you want more detail, another table provides it. Compared to an ‘average’ fielder, you can look how far an outfielder traveled in the first 1.5 seconds (react), the second 1.5 seconds (burst), and distance subtracted by an indirect route (route). This table is called the jump leaderboard. A snip of the screen follows.

For a specific player (in this case David Peralta), you can look at estimated & actual catch success rate and jump data on one page.

Ultimate Zone Rating (UZR) is provided at Fangraphs, and Defensive Runs Saved (DRS) is provided at Fielding Bible.

Both UZR and DRS make many complex adjustments to more accurately measure defensive prowess. Player leaderboards links are UZR and DRS. Team DRS link is here.

A snip of the Diamondbacks UZR leaderboard follows. The on-line screen has a ‘MORE’ button that can be used to reveal the entire table. Each player has a separate line for each position that he played. For example, Jake Lamb is shown with a 4.7 UZR/150 in 83 innings at first base, and farther down in the table he is shown with a 17.5 UZR/150 in 16 innings at third base. In left field Daulton Varsho had a 32.1 UZR/150 in 43 innings.

UZR throws out plays that include a shift. UZR adjusts for type of player (ie second baseman or third baseman), and adjusts for ballpark. UZR provides components — for outfielders they are range, error, and arm, and for infielders they are range, error, and double plays. UZR is used to calculate WAR at FanGraphs.

“While both [UZR and DRS] get their data from BIS and use very similar methods (especially in the Plus/Minus calculation), DRS has batted ball timer data, while UZR does not. The [Good Fielding Plays/Defensive Misplays] GFP/DME system is also exclusive to DRS, while UZR attempts to measure something similar by adding up errors.” – dan_bot.

DRS is used to calculate WAR at Baseball Reference. This article lists inputs to DRS based on position:

Corner Infielders: Plus/Minus, double plays, bunt fielding, GFP/DME.
Middle Infielders: Plus/Minus, double plays, GFP/DME
Outfielders: Plus/Minus, outfield throws, GFP/DME
Catchers: Pitcher handling, baserunning prevention, bunt fielding, GFP/DME
Pitchers: Plus/Minus, baserunning prevention, bunt fielding, GFP/DME

DRS was updated prior to the 2020 season. The new system includes ‘PART.’ On shifted plays, players receive credit based on where they stood when the ball was hit. Replacing “Range and Positioning Runs Saved,” are three statistics “Air, Range, And Throwing Runs Saved.” A snip of the DRS page for Ketel Marte follows. As the chart shows, infield and outfield defense are different.

SABR Defensive Index (SDI) is provided at SABR.

SDI is used for Gold Glove Awards. A download of the 2013 Excel file, which includes text of of formulas that calculate SDI, can be found on this webpage.

The SDI formulas include three zone metrics (Total Zone (TZ), Defensive Runs Saved (DRS) and Ultimate Zone Rating (UZR)), and two play-by-play metrics (Runs Effectively Defended (RED) and Defensive Regression Analysis (DRA)). It could be useful if I knew where to find data more recent than 2013. In 2013 Paul Goldschmidt won a gold glove, and Patrick Corbin was a finalist. The Excel file looks similar to the following: