DRS
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 are measured in “runs” above or below average, and Baseball Info Solutions data is used as an input. Since DRS is measured in runs, it can be compared easily with a player’s offensive contributions (wRAA or similar statistics).
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.
For information about defensive metrics in general, see our Overview section.
Calculation:
The full explanation of how DRS is calculated is a tad involved — see this FAQ page for more detailed information.
Why DRS?
This isn’t the right place to debate DRS versus another similar metric, but you should use a metric like DRS or UZR because it is a better representation of defensive value than something like fielding percentage. Even your eyes aren’t going to do a great job measuring defensive performance because you simply can’t watch and remember enough plays a year to have a good sense of exactly how well a player stacks up against the competition. You might be able to judge a single play better than the metrics (although that’s debatable), but your ability to recall every play and compare them is limited. Run value defensive stats like DRS provide you with the best estimate of defensive value currently available and allow you to estimate how much a player’s defense has helped his team win.
How To Use DRS?
DRS is as easy to read as it is difficult to calculate. DRS tells you how many runs better or worse that player has been relative to the average player at his position. A +5 DRS at third means the player is five runs better than the average third baseman.
There are some reasons for caution, however. First, DRS is relative to positional average so you want to factor in the fact hat some positions are harder to play than others. For that reason we have the positional adjustment, which we add to UZR to get DEF. If you prefer DRS, you could add DRS to the adjustment and get a DRS-based DEF.
The other thing to remember is that DRS isn’t going to work well in small sample sizes, especially a couple of months or less. Once you get to one and three-year samples, it’s a relatively solid metric but defensive itself is quite variable so you need a good amount of data for the metrics to become particularly useful. There’s plenty more to say about this issue, but that’s for another entry. In general, DRS isn’t perfect because it doesn’t factor in shifts, positioning, and can’t perfectly measure everything it needs to, but it’s still among the best options out there.
Context
Defensive statistics should not be taken as 100% accurate, just like anything. There are plenty of reasons why they might not be telling you a complete story, and the Overview section goes into a lot of detail about that. As far as interpreting DRS, if you’ve gotten to that point, the scores can be broken down into the following tiers. This is a good shorthand way of evaluating a player’s defensive ability level:es.
DRS scores can be broken down into the same general tiers as UZR:
| Defensive Ability | DRS |
|---|---|
| Gold Glove Caliber | +15 |
| Great | +10 |
| Above Average | +5 |
| Average | 0 |
| Below Average | -5 |
| Poor | -10 |
| Awful | -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 StatCast 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 UZR 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:
Difference Between UZR and Plus/Minus – The Book Blog
Piper was the editor-in-chief of DRaysBay and the keeper of the FanGraphs Library.
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I am confused, and cannot find a good answer on other sites I have looked at, as to how the +/- system is calculated. When Posnanski describes it based on “making the play” or not, is the throw weighted differently than the catch? For example, if a 3B makes a spectacular catch on a grounder down the line but botches the throw, is that missed play calculated differently than if the player had simply missed the catch? In the former situation it would seem that the player should get credit for the catch even though an error was made on the throw. Just wondering.
Hope your math skills are considerably better than your writing ability. So many typos in this article it’s tough to take seriously.
As for DRS, you might not be able to develop a less-accurate measure of defensive performance if you tried. Those of us who REALLY UNDERSTAND baseball know who the best defensive players are at every position. If you require formulas, calculations, algorithms, etc. in your (failed) attempts to identify those players, please stay away from baseball and just stick with math.