Plus/Minus & Runs Saved FAQ

Baseball Info Solutions has just released a more comprehensive FAQ on their fielding system, which we list on FanGraphs as DRS (and the various components that make up DRS).

It goes into details about how they make adjustments for various positions, ball hogging, home runs saved, the Green Monster, player positioning, etc….

Click to read the FAQ

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David Appelman is the creator of FanGraphs.

7 Responses to “Plus/Minus & Runs Saved FAQ”

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  1. vtsoxfan says:

    I don’t see any mention of scoops for first basemen. With such an otherwise-comprehensive system (Bunt Runs Saved, Double Play Runs Saved), why not show this? Tango estimated that the magnitude of scooping ability was at best +4 runs. However, I thought his methodology was a bit questionable, given that he was scraping play-by-play data from STATS rather than looking at actual video like BIS does. The difficulty of judging scoops, of course, is that it’s a matter of inches between “a bad throw that a good first baseman can reach” and “a bad throw that even a good first baseman would be pulled off the bag by.” But maybe the folks at BIS could come up with some interesting analytical rubric for judging scoops.

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    • Chris H says:

      I don’t think Baseball Info Solutions is responsible for the Scoops stat. I believe that’s just a counting statistic that is kept.

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    • BenJ says:

      Scoops are part of the Good Fielding Plays/Defensive Misplays system, which is an entirely separate BIS set of data.

      Other than HR Saving Catches, none of the GFPs/DMs factor into The Fielding Bible Defensive Runs Saved stats.

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  2. Darren says:

    I am not sure why they use only one years worth of data, rather than many years. The sample size is too small. If they are concerned about not having the +/- adding up to zero each year, they can re-adjust each year like UZR.

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  3. pft says:

    When I look at DRS at the team level in 2010, it does not add up to 0. The sum total of all teams DRS is 446.

    If there is a reasonable explanation, I am all ears.

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    • BenJ says:

      Just added it to the FAQ at the link shown. I meant to add it in there the first time around.

      “Why doesn’t Runs Saved add up to zero for the whole league?

      There are a few Runs Saved components that don’t naturally zero out for a variety of reasons. In many cases, it’s difficult or impossible to accurately determine both when a player does a particular thing well and when they do it poorly, the plus and the minus, if you will.

      Outfielder Arms- the runner advancement portion (first-to-third, second-to-home, and first-to-home situations) is zeroed out. There are also “Miscellaneous Kills”, which come on other types of runner-advancement plays, where it is very difficult to accurately measure “opportunities”. The solution developed in The Fielding Bible – Volume II was to apply a straight run value of .75 Runs Saved to each of these.

      HR Saving Catches- similar to the above, it’s difficult to determine when an outfielder should have made a HR Saving Catch but didn’t so we could penalize them for *not* robbing home runs.

      Plus/Minus- Since we begin using a rolling one-year basis for the Plus/Minus system, the mid-season numbers can fluctuate but will settle out at zero by the end of the year.

      For bunts and double plays, we used fixed constants that don’t necessarily even out each individual season.

      Lastly, there’s some rounding error, since each component is rounded then added to get Total Runs Saved.

      As a result of all of these, Plus/Minus isn’t centered at zero or any other number for every position. If you’re looking to center Total Runs Saved or each category at zero for your own purposes, it wouldn’t be too difficult to scale each player up or down based on their innings played at the position. “

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      • pft says:

        Thanks, I did not realize that. UZR and Dials DRS do sum to 0, and since it is runs saved above average, not sure I agree that it should not. Guess I need to ponder this some more.

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