Defensive Runs Saved (DRS) is a defensive statistic calculated by The Fielding Bible, an organization run by John Dewan, that rates individual players as above or below average on defense. Much like UZR, players as measured in “runs” above or below average, and Baseball Info Solutions data is used as an input.
The full explanation of how DRS is calculated is a tad complicated — see this FAQ page for more detailed information — but in simple terms:
“…as I understand it, the numbers determines (using film study and computer comparisons) how many more or fewer successful plays a defensive player will make than league average. For instance, if a shortstop makes a play that only 24% of shortstops make, he will get .76 of a point (1 full point minus .24). If a shortstop BLOWS a play that 82% of shortstops make, then you subtract .82 of a point. And at the end, you add it all up and get a plus/minus.” (Joe Posnanski, Sports Illustrated)
FanGraphs reports a large number of fielding calculations using this system, all of them measured in runs above average. Descriptions come from the Fielding Bible website:
rSB – Stolen Base Runs Saved (Catchers/Pitchers) measures two things: the pitcher’s contributions to controlling the running game, and gives the catcher credit for throwing out runners and preventing them from attempting steals in the first place.
rBU – Bunt Runs Saved (1B/3B) evaluates a fielder’s handling of bunted balls in play.
rGDP – Double Play Runs Saved (2B/SS) credits infielders for turning double plays as opposed to getting one out on the play.
rARM – Outfield Arms Runs Saved evaluates an outfielder’s throwing arm based on how often runner advance on base hits and are thrown out trying to take extra bases.
rHR – HR Saving Catch Runs Saved credits the outfielder 1.6 runs per robbed home run.
rPM – Plus Minus Runs Saved evaluates the fielder’s range and ability to convert a batted ball to an out.
DRS – Total Defensive Runs Saved indicates how many runs a player saved or hurt his team in the field compared to the average player at his position.
To reiterate, Defensive Runs Saved (DRS) captures a player’s total defensive value.
Before drawing any conclusions about a player’s defense, look at a full three years of defensive data, drop the decimal points and take an average, and compare DRS scores with other defensive metrics (UZR, TZL, etc.). By taking a broader picture, you will help ensure that you’re not being over-confident or overstating a player’s defensive abilities.
DRS scores can be broken down into the same general tiers as UZR:
|Gold Glove Caliber||+15|
Things to Remember:
● Looking for even more information on how DRS is calculated? Head over to the Fielding Bible, where you can find an extensive article that explains their process in detail.
● DRS uses Baseball Info Solutions (BIS) data in calculating its results. It’s important to note that this data is compiled by human scorers, which means that it likely includes some human error. Until FIELDF/x data gets released to the public, we are never going to have wholly accurate defensive data; human error is impossible to avoid when recording fielding locations by hand, no matter how meticulous the scorers. That said, BIS data is still the best, most accurate defensive data available at this time, so just be careful not to overstate claims of a player’s defensive prowess based solely on defensive stats.
● DRS is comparable to UZR in terms of methodology (e.g. the use of “zones” for evaluating defensive success rates) and results. There are some slight differences between the two systems (see below), so DRS and UZR will occasionally disagree on how to rate certain players, but they agree more often than they disagree. The differences between the two systems are smaller than they seem at first glance:
Both systems have the same goal- estimate a player’s defensive worth in units of “runs”, and both rely on hit location and type data from Baseball Info Solutions. The differences lie in the various adjustments and calculations that are made.
For example, Defensive Runs Saved uses a rolling one-year basis for the Plus/Minus system, while Lichtman uses several years of data to determine each play’s difficulty level. Defensive Runs Saved also includes components to measure pitcher and catcher defense. (The Fielding Bible)
Links for Further Reading: