DALLAS (105.3 The Fan) - Defensive Runs Saved (DRS), a metric used to assess defensive ability, measures a player's "total" defensive value relative to league average. In order to do this, there are a number of elements that go into coming up with this particular metric.
Among all the elements, the "Plus/Minus" component plays the largest role in generating a DRS value. Plus/Minus is calculated with the help of data from Baseball Info Solutions (BIS), a commercial provider of baseball statistical information. Every MLB play is entered into the BIS database, which records the direction, distance, speed, and type of every batted ball.
Speed is scored as either soft, medium, or hard. Batted ball types include bunt, groundball, line drive, fly ball, and, introduced in 2006, "fliner." A fliner is a ball that exists somewhere between a fly ball and a line drive.
So, stay with me here...
Let's say Rangers centerfielder, Danny Santana, catches a ball in the left-center field alley and BIS data indicates that similar fly balls get caught 70% of the time. If that's the case, Ian would gain 0.3 points, parallel to the 30% degree of "beyond the norm" difficulty of the play. If he were unable to make the play, he'd suffer a -0.7 grade, in concert with the data that suggests the play gets made 70% of the time.
This process is continued throughout the game with a plus/minus score being assessed.
Now, we're not quite done with the Plus/Minus portion of the calculation just yet.
There are three levels of adjustments.
1) Park adjustments: This is where the metric takes into account the quirks of each park and how it impacts the data.
2) Season-long adjustments: Using the example involving Ian Desmond above, let's say he made that play on June 15th and on that date similar plays had been converted into outs 70% of the time. Then on August 15th it turns out similar plays would be converted into outs just 65% of the time, then Desmond's score would be adjusted to that updated figure. Thus, every play is essentially fluid in its value until the season ends.
3) Positional adjustments: Every position has at least one special adjustment for the sake of accuracy and to incorporate that spot's nuance. For instance, plays involving a first baseman are categorized by those in which he is and isn't holding on a runner, since it significantly impacts positioning.
One consideration for the calculation of this metric is the "ball-hogging problem." This is where one fielder makes a play that could have been made by another fielder. In this case, the player who did not make the play is not penalized just because someone else made the play, even if the ball was hit into his "range."
What about when a play isn't made, but could have been made by two different fielders? Well, if a ball is hit between two outfielders in the gap and it falls for a base hit, even though similar balls had been converted into outs during the season, only the player who was most likely to make the play gets penalized for not doing so. For instance, if centerfielders typically catch that ball in the gap 60% of the time, but leftfielders just 35% of the time, than only the centerfielder gets penalized.
So that's a general understanding of the Plus/Minus component, but there are still other methodologies involving specific parts of the game that factor into a player's DRS score. You ready?
Stolen Base Runs Saved (rSB) measures both the pitcher's ability to control the running game as well the catcher's ability to not only throw runners out, but to also prevent them from running in the first place.
Bunt Runs Saved (rBU) calculates a first and third baseman's ability to handle bunted balls.
Double Play Runs Saved (rGDP) credits middle infielders for their ability to get both outs in double-play scenarios.
Outfield Arms Runs Saved (rARM) evaluates an outfielder's arm based on how often a runner advances on base hits and their ability to throw someone out trying to take an extra base.
Home Run Saving Catch Runs Saved (rHR) credits an outfielder with 1.6 runs saved for every robbed home run.
All those methodologies in addition to Plus/Minus and the proper adjustments create Defensive Runs Saved.
Now the question becomes: how is it used?
Casually, it is a great way to compare defensive players with their positional peers. With the unique parts of each position, it is tough to compare a player's DRS across positions. If you want to know how good Adrian Beltre was defensively, however, you can certainly compare his DRS to other third basemen's to get a good read.
Those in Major League Baseball whose responsibilities emphasize the understanding and application of advanced metrics aren't quite sure what to make of DRS just yet. Most teams do their own data collecting and feel like DRS, which is still a new, developing stat, has some fine-tuning to do with its quantitative methodologies. When it comes to defensive metrics, in general, there is still a lot of work being done to try and account for the differences between strong pre-play positioning versus fielding skill.
Only the fielder who makes the play gets credit. For instance: a ball is hit in the right-centerfield gap and is typically caught by the centerfielder. The centerfielder gets a bad read and the play is made by the rightfielder. Thus, the rightfielder will receive credit for the play, however, the centerfielder does not receive any form of penalty which, in some cases, is an example of how this statistic, not unlike any individual statistic, does not provide an absolute reflection of defensive ability.
While defensive metrics have plenty of development ahead to gain the trust of those inside MLB front offices, DRS is certainly blossomed into a great way to gauge a player's defensive season, even if it is with a grain of salt.
