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Thread: John Dewan - Defense worth 50% of offense

  1. #1
    The Boss dougdirt's Avatar
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    John Dewan - Defense worth 50% of offense

    From http://actasports.com/sow.php?id=203

    The most significant discovery of my career

    March 12, 2009

    About two weeks ago The Fielding Bible—Volume II went to print. Since then, as I've been studying some of the data in the book preparing for interviews, I came upon a discovery that was truly amazing to me. The most amazing, and significant, discovery of my 25 years in the baseball analysis business.

    The key mission of the second volume of The Fielding Bible was to translate all of our new defensive methods into one common number that would be understandable by everyone. That number is Defensive Runs Saved. How many runs does a player save for his team defensively?

    We look at each player individually. We then do a team summary by adding up all the individual players. How many runs does an above-average defense save compared to an average team? The team with the best defense in baseball in 2008 was the World Champion Philadelphia Phillies. By combining all of our defensive methods, eight different methods across the nine positions in baseball, we estimate that the Phillies defense saved 78 runs. Using the rule of thumb that 10 runs is equivalent to one win, that's eight wins. With an average defense, the Phillies wouldn't have had even a sniff of the playoffs.

    The worst defensive team in baseball in 2008? The Kansas City Royals. Their defense cost them about 48 runs relative to the average team. Comparing the Phillies and the Royals, the difference between the best and worst defensive teams in baseball was about 130 runs.

    Now, remember that number. 130.

    The best run-scoring team in baseball was the Texas Rangers with 901 runs in 2008. The San Diego Padres were the worst with 637 runs. That's a difference of about 260 runs.

    Here's the discovery, and I found it because the numbers just jumped out. The 130 difference in runs saved on defense is exactly half of the 260 difference in runs scored. That's exactly half. The implication is that defense is worth about half as much as offense.

    That's a lot higher than I would have guessed, and a lot higher than I think most people would guess. But the numbers are remarkably consistent from one year to the next:
    Code:
    Year 	Best to Worst Offensive Difference 	Best to Worst Defensive Difference 	Defensive Spread
    as Percentage of Offensive Spread
    2008 	264 	126 	48%
    2007 	295 	141 	48%
    2006 	241 	114 	47%
    Everyone realizes that defense is important, but it's never been quantified. Now we have the first way to quantify it. It's not necessarily the best way, and there will be more to come on this issue. The 50% figure is more of an indicator than an exact number, but it just jumped out at me and I wanted to share it with you.

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    Stat Wanker Hodiernus RedsManRick's Avatar
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    Re: John Dewan - Defense worth 50% of offense

    There's an important distinction to be made here.

    A run prevented is "worth" just as much as a run scored scored when it comes to winning baseball games. And without dollar values put against offensive and defensive production, it's hard to say which costs more.

    Rather, the point Dewan is making is that there is more room for variance when it comes to offense than when it comes to defense. A great offense puts you further ahead of the pack than a great defense. A poor offense leaves you further behind than a poor defense. Take an elite offensive player at a position who gives you replacement defense and he's doing significantly more to help your team win than the elite defender who is replacement level defensively. Hanley Ramirez >> Omar Vizquel. It's not really news.

    The 2:1 ratio is interesting, but I'm not sure what he would have us do with it. The real trick comes in figuring out how you acquire each. How much does a run prevented cost compared to a run scored? If you find out that a run prevented only costs $200k and a run scored costs $500k, that's something you can make decisions with.
    Last edited by RedsManRick; 03-13-2009 at 07:35 PM.
    Games are won on run differential -- scoring more than your opponent. Runs are runs, scored or prevented they all count the same. Worry about scoring more and allowing fewer, not which positions contribute to which side of the equation or how "consistent" you are at your current level of performance.

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    Five Tool Fool jojo's Avatar
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    Re: John Dewan - Defense worth 50% of offense

    The distinction that Dewan needs to make is that fielding is worth roughly 1/2 of offense. This is a case where definitions are vital for accuracy.

    And truthfully, Dewan needs to get out more if he truly believes he's discovered something.
    Last edited by jojo; 03-13-2009 at 08:05 PM.
    "This isn’t stats vs scouts - this is stats and scouts working together, building an organization that blends the best of both worlds. This is the blueprint for how a baseball organization should be run. And, whether the baseball men of the 20th century like it or not, this is where baseball is going."---Dave Cameron, U.S.S. Mariner

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    Charlie Brown All-Star IslandRed's Avatar
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    Re: John Dewan - Defense worth 50% of offense

    Quote Originally Posted by RedsManRick View Post
    The 2:1 ratio is interesting, but I'm not sure what he would have us do with it. The real trick comes in figuring out how you acquire each. How much does a run prevented cost compared to a run scored? If you find out that a run prevented only costs $200k and a run scored costs $500k, that's something you can make decisions with.
    Without taking a position on whether that 50% is accurate, I'd argue the ratio -- be it Dewan's or anyone else's -- is a keystone to plenty of other numbers.

    You can't value a position player without expressly or implicitly attaching a run value (plus or minus) to his defensive value. And you can't do that without figuring out his defensive ability relative to his positional peers AND staking out a position on how much defense is worth in the first place. Without a solid working answer to the second question, it's all just guessing.
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    KungFu Fighter AtomicDumpling's Avatar
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    Re: John Dewan - Defense worth 50% of offense

    Leave it to the guy that makes his living selling defensive metrics to overstate the importance of defensive metrics.

    It is no surprise that exaggerating the number of runs saved/lost by fielding will inflate the ratio of fielding to offense.

    Asking John Dewan to place a value on defensive metrics is like asking the owner of Jiffy Lube how often you should have your oil changed.

    How many copies of the Fielding Bible would he sell if he estimated that fielding didn't have much impact on run scoring? It is in his financial best interest to advertise the importance of fielding.

    If you want a fair appraisal you should rely on a neutral appraiser rather than trust someone with a vested interest in the outcome.

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    The Boss dougdirt's Avatar
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    Re: John Dewan - Defense worth 50% of offense

    Quote Originally Posted by AtomicDumpling View Post
    Leave it to the guy that makes his living selling defensive metrics to overstate the importance of defensive metrics.

    It is no surprise that exaggerating the number of runs saved/lost by fielding will inflate the ratio of fielding to offense.

    Asking John Dewan to place a value on defensive metrics is like asking the owner of Jiffy Lube how often you should have your oil changed.

    How many copies of the Fielding Bible would he sell if he estimated that fielding didn't have much impact on run scoring? It is in his financial best interest to advertise the importance of fielding.

    If you want a fair appraisal you should rely on a neutral appraiser rather than trust someone with a vested interest in the outcome.
    Not exactly Dewan being the only one agreeing with what he is suggesting.

    More, and better discussion over at BBTF.

    Tango has some good stuff in there.

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    High five! nate's Avatar
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    Re: John Dewan - Defense worth 50% of offense

    It might be fair to say that over the past three years, league-wide, fielding has been worth 50% of offense but I'm not sure that trickles down to teams and individual players in the same proportion.
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    Member ochre's Avatar
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    Re: John Dewan - Defense worth 50% of offense

    Great. Now how much impact does pitching have on defense?
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    The Boss dougdirt's Avatar
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    Re: John Dewan - Defense worth 50% of offense

    Quote Originally Posted by ochre View Post
    Great. Now how much impact does pitching have on defense?
    There are a few varying opinions on that really. There is some good reading on just that over at the BBTF link I provided a few posts up.

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    Re: John Dewan - Defense worth 50% of offense

    Quote Originally Posted by dougdirt View Post
    Not exactly Dewan being the only one agreeing with what he is suggesting.

    More, and better discussion over at BBTF.

    Tango has some good stuff in there.
    Right. Tango has argued for a split of offensive being 42%, pitching being 33%, and fielding being 25% when breaking the talent distribution out into those components.

    Dewan isn't overstating the contribution of defense. He's just guilty of not realizing he hooked a fish that has already been caught.

    It's kind of a shocking thing for him to not appreciate.
    "This isn’t stats vs scouts - this is stats and scouts working together, building an organization that blends the best of both worlds. This is the blueprint for how a baseball organization should be run. And, whether the baseball men of the 20th century like it or not, this is where baseball is going."---Dave Cameron, U.S.S. Mariner

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    Five Tool Fool jojo's Avatar
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    Re: John Dewan - Defense worth 50% of offense

    Quote Originally Posted by AtomicDumpling View Post
    Leave it to the guy that makes his living selling defensive metrics to overstate the importance of defensive metrics.

    It is no surprise that exaggerating the number of runs saved/lost by fielding will inflate the ratio of fielding to offense.

    Asking John Dewan to place a value on defensive metrics is like asking the owner of Jiffy Lube how often you should have your oil changed.

    How many copies of the Fielding Bible would he sell if he estimated that fielding didn't have much impact on run scoring? It is in his financial best interest to advertise the importance of fielding.

    If you want a fair appraisal you should rely on a neutral appraiser rather than trust someone with a vested interest in the outcome.
    I'm sorry but this isn't a valid criticism of Dewan's system or his position on the value of defense relative to the value of offense.

    When those kind of charges of bias are evoked to discredit a position, there should really be concrete, specific examples to bolster them.
    Last edited by jojo; 03-13-2009 at 09:39 PM.
    "This isn’t stats vs scouts - this is stats and scouts working together, building an organization that blends the best of both worlds. This is the blueprint for how a baseball organization should be run. And, whether the baseball men of the 20th century like it or not, this is where baseball is going."---Dave Cameron, U.S.S. Mariner

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    Posting in Dynarama M2's Avatar
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    Re: John Dewan - Defense worth 50% of offense

    Not exactly a eureka moment there for Dewan. First off, comparing the difference between the best and worst in offense and defense is a pretty arbitrary measure of the actual value of those things.

    Second, you're comparing one actual thing (offense) with one highly theoretical thing (runs saved/cost on defense). The best Dewan can say is he thinks that's where the defense landed.

    Third, if he's right, then the real revelation isn't that defense is worth 50% of offense, it's that it's exactly as valuable as pitching. Half the game is scoring runs, half the game is preventing runs. If defense is more valuable than we thought, then the thing that becomes less valuable is pitching.
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    Member ochre's Avatar
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    Re: John Dewan - Defense worth 50% of offense

    Quote Originally Posted by M2 View Post
    Not exactly a eureka moment there for Dewan. First off, comparing the difference between the best and worst in offense and defense is a pretty arbitrary measure of the actual value of those things.

    Second, you're comparing one actual thing (offense) with one highly theoretical thing (runs saved/cost on defense). The best Dewan can say is he thinks that's where the defense landed.

    Third, if he's right, then the real revelation isn't that defense is worth 50% of offense, it's that it's exactly as valuable as pitching. Half the game is scoring runs, half the game is preventing runs. If defense is more valuable than we thought, then the thing that becomes less valuable is pitching.
    I read it as him saying that the pythag theory is valid. No more no less. I'm probably over-simplifying, though. I had the odd impression he was saying that if you divide the circumference of a circle by it's diameter you'll always get teh same number.

    It's more interesting to know the relationship between pitching and fielding. Offense vs. Defense is pretty straight forward. Score more runs than you allow and you win.
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    post hype sleeper cincinnati chili's Avatar
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    Re: John Dewan - Defense worth 50% of offense

    Quote Originally Posted by M2 View Post
    Not exactly a eureka moment there for Dewan. First off, comparing the difference between the best and worst in offense and defense is a pretty arbitrary measure of the actual value of those things.

    Second, you're comparing one actual thing (offense) with one highly theoretical thing (runs saved/cost on defense). The best Dewan can say is he thinks that's where the defense landed.

    Third, if he's right, then the real revelation isn't that defense is worth 50% of offense, it's that it's exactly as valuable as pitching. Half the game is scoring runs, half the game is preventing runs. If defense is more valuable than we thought, then the thing that becomes less valuable is pitching.
    Bill James said years ago that a lot of what we consider to be "pitching" is actually "defense." I'm very skeptical that defense accounts for 50% of run prevention at the major league level. Am I correct that about 1/4 of outs come from strikeouts and about a half of the remainder are can-o-corn outs (or non-x-chances for the strat geeks)? Plus the variance in the non-can-o-corn outs doesn't strike me to be nearly as pronounced as the variance in hitters.
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    KungFu Fighter AtomicDumpling's Avatar
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    Re: John Dewan - Defense worth 50% of offense

    Quote Originally Posted by jojo View Post
    I'm sorry but this isn't a valid criticism of Dewan's system or his position on the value of defense relative to the value of offense.

    When those kind of charges of bias are evoked to discredit a position, there should really be concrete, specific examples to bolster them.
    Apparently you missed the point.

    The point is you can't trust the words of a salesman. Don't believe the hype.

    My point was not a criticism of Dewan's system and had nothing to do with the ratio of offense to defense.

    Fielding is half as important as offense? Not worthy of a response really. I won't be rushing out to by his latest book.
    Last edited by AtomicDumpling; 03-14-2009 at 02:52 AM.


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