M’s Defense And The Fielding Bible

Dave · March 13, 2009 at 8:59 am · Filed Under Mariners 

You may have already seen Baker’s post about John Dewan ranking the Mariners as an above average defense in 2008, according to his Defensive Runs Saved metric introduced in the newly published Fielding Bible II.

I don’t have tons of time to walk everyone through why Dewan is wrong – and, I should point out that The Fielding Bible is a really good read with lots of great stuff, and that BIS has been instrumental in bringing advanced defensive measures to the forefront of baseball, so this isn’t in any way an attack on him or the the book – but there’s some problems with his Defensive Runs Saved metric.

If you want to read some more in depth conversations about some of the issues, here and here are good places to start.

But, for those of you who would prefer a short summary, here’s the basic problem – Dewan/James calculated that each play made in the OF is worth about .56 runs, while play made in the infield is about +.75 runs (numbers are from memory, I don’t have the book in front of me right now, but they’re close). I think that’s just demonstrably wrong. We know, thanks to linear weights, that the value of an out is about -0.27 runs, and the value of a single is +0.47 runs, so making a save on a play that would have otherwise gone for a single is worth ~+.71 runs. However, the run values of doubles and triples are .77 and 1.04, respectively, so turning potential extra base hits into outs is more valuable than turning singles into outs.

Obviously, a great majority of doubles and triples come on fly balls to the outfield, and because of that, there’s almost no way to realistically conclude that a play saved on the infield is worth more than a play saved in the outfield. But that’s the conclusion that Dewan/James came to, and part of why they have the Mariners rated as above average – infield defense is significantly more important in their system than outfield defense, and so by reducing the the value of the M’s weakest link (OF defense), it serves to make the M’s look better than they were.

There’s also positioning issues in how Dewan ended up calculating his +/- ratings, as can be seen best in his Chase Utley numbers. Because Utley shifts towards the first base bag to make up for Ryan Howard’s ridiculous lack of range, he gets to far more balls in the 1B/2B hole than most second baseman. Dewan doesn’t adjust for this, and gives Utley credit for a +32 rating to his left (compared to +6 straight on and +8 to his right). Because of how Dewan is measuring plays saved (based on normal positioning for all players across the league), Utley would look worse defensively by his system if the Phillies just got a better defensive first baseman and Utley shaded back towards the 2B bag to play a more normal second base. Giving Utley credit for Howard being awful isn’t really what we are trying to do.

There are some other issues (he’s not using context neutral numbers, James’ new Defensive Misplays is pretty subjective and all plays are weighted evenly), but those two are the big reasons why Dewan’s Defensive Runs Saved doesn’t line up with the other advanced defensive metrics. And, to me, they’re problems, not enhancements.

The UZR data that we publish at FanGraphs is based on the play by play data collected by Baseball Info Solutions. It’s the same data, but a somewhat different (in my opinion, better) methodology for converting that data into runs saved. As you know, UZR had the Mariners at -21.6 runs for 2008, thanks mostly to a -16.8 rating from their outfielders. This is, honestly, the more reliable number to use. It’s based on exactly the same data, and the discrepancies between the two systems lie mostly in some assumptions made by Dewan that I would consider fairly questionable.

So, don’t make too big a deal out of this, and don’t buy into the rhetoric of the M’s defensive upgrades only getting them from a 62 to 64 win team. Right now, this is a ~79 win team, and an improved outfield defense is a significant part of why the team will be a lot better this year than last.


69 Responses to “M’s Defense And The Fielding Bible”

  1. Jeff Nye on March 13th, 2009 2:43 pm

    I never said Raul is “the superior player” once.

    In run production, Raul bests Chavez by far more than the +3 (according to a previous poster) Chavez can boast over Raul defensively.

  2. rmac1973 on March 13th, 2009 2:43 pm

    [you’ve derailed this comment thread enough]

  3. Mike Snow on March 13th, 2009 2:45 pm

    Actually, I have looked, not that it’s my responsibility to find support for a position I disagree with. And I’ve come up empty for people arguing such a position outside of this comment thread. If you want to continue making arguments based on it, show your work.

  4. Alex on March 13th, 2009 3:11 pm

    If you want to use 2008 offensive stats, Ibanez is 3-4 wins over Chavez (36 runs that Dave mentioned) and Chavez is 2-3 wins over Ibanez defensively (I’d say 3).

    Overall: Ibanez is at most 1 win better overall (this is if you project their 2009 offense to be equal to 2008).

    This doesnt make up for the fact that we dont have to pay Ibanez’ contract, and we also get TWO early draft picks for ‘losing’ Ibanez.

    Replacing Ibanez with Chavez gives us new talent (draft picks) and saves a lot of money (allowing the team to improve in other areas in the future), while giving up almost nothing. (or if you use slightly different numbers, then we’re actually giving up nothing or possibly improving slightly)

  5. Tuomas on March 13th, 2009 3:14 pm

    So, um.

    Plus, using Chavez instead of Ibanez might make Washburn look decent enough that he can be flipped for a C- prospect. That’s definitely phenomenal upside.

  6. Jeff Nye on March 13th, 2009 3:38 pm

    Honestly, I’d take used Big League Chew for Washburn just to get some salary relief.

  7. joser on March 13th, 2009 3:46 pm

    And it’s not just Washburn. Improving the defense makes all the pitchers look better, and improving the outfield defense certainly makes the flyball pitchers look better (like, as you say, Washburn). So even if no one is willing to take Washnurn, the team may be able to trade high on someone else. I’d hate to see RRS go have a good career elsewhere, for example, but I certainly could live with it if he was part of a package that brought some plus talent in return.

    I think run scoring will always tend to be slightly more highly valued than run prevention, for two reasons…

    This may be true, but there’s no reason the run scoring has to come from the LF position. Replacing Raul’s run production with equivalent run prevention in the outfield, and then upgrading from Sexson and Vidro’s non-production, is a significant net improvement. And that’s even before you get to contracts and draft picks.

  8. Jeff Nye on March 13th, 2009 3:49 pm

    Oh, absolutely. Run scoring doesn’t have to come from anywhere in particular.

    Well, it helps when your DH is a positive run producer, I guess. We miss you, Turbo!

  9. DMZ on March 13th, 2009 4:27 pm

    six or seven months ago, FYI, so you might also look for yourself.

    Yeah Mike, go figure out what blog he discovered via baseball-reference six or seven months ago.

  10. Kunkoh on March 13th, 2009 5:26 pm

    I’m confused, why is a 31yr old expected to age worse than a 36/7 yr old?

    I think the upgrades at defense LF, CF, and even 1b should be a nice improvement compared to last year. I’m more excited about this year than I’ve been in years. No, we may not be a great team, but we are a heck of a lot better than last year and that should make things a lot more interesting.

  11. Sidi on March 13th, 2009 11:38 pm

    IMHO, you cannot win any baseball game by a score of 0-0: great defense only gets you so far – boasting the league’s best UZR doesn’t push runs across the plate.

    But even a team of pitchers is going to score some runs. Hell, you could throw nine/ten of me into the game, and I think I would have better than even odds of scoring a run in 162 games. Especially considering that, for even $400k, I would be diving into pitches like crazy.

    The whole “0-0” crap misses a huge point, the difference between a “good” hitter and “terrible” hitter in MLB really isn’t as large as people think. You get a hit 1/3 of the time, you’re good, but a hit 1/4 of the time you suck. You get on base 40% of the time, you’re amazing, but at 30% you’re worse than Willie Boom Boom.

  12. anchorjim on March 14th, 2009 12:53 am


    After seeing tangotiger’s explanation of Dewan’s 0.77 for infield plays vs. outfield plays, do you still feel that Dewan’s numbers are demonstrably wrong?

  13. Osfan on March 14th, 2009 3:18 am

    But even a team of pitchers is going to score some runs.

    Especially if they were all Felix’s.

  14. studes on March 14th, 2009 4:02 am

    Dave, I haven’t red the entire thread, but what you’re saying isn’t true. Dewan’s system isn’t based on outs saved, it’s based on bases saved. Outfielders save more bases per out saved, so the value per base is less than then value per out (comparing outfield to infield).

  15. Breadbaker on March 14th, 2009 4:06 am

    This Utley-Howard thing reminds me of the Phillie-related debate James described in an earlier abstract, where he debunked Larry Bowa’s fielding prowess. People were saying things like “well, look at all the balls Mike Schmidt fields which Bowa might have gotten to” and James basically said “if there are two players who can get to the ball, then one of them ought to move over.”

    This is, effectively, the flipside of it. Utley is getting balls that someone else ought to get but isn’t. So how do you properly credit him with them (after all, he really does field them)? More importantly, how do you rate him when he’s essentially playing a different position from all the other second basemen?

  16. studes on March 14th, 2009 4:07 am

    Plus, he doesn’t use the defensive misplays to calculate runs saved per team. That’s an entirely different system.

    I humbly suggest that you post a correction to this post.

  17. coasty141 on March 14th, 2009 8:41 am

    I think its kind of interesting that Utley/Howard is being discussed so much in this post. Why aren’t we talking about Beltre/Betancourt? It seems as though the relationship between those two fielders is more pertinent to the topic of discussion.

  18. qwerty on March 14th, 2009 10:26 am

    your reasoning made 1.73 more sense than theirs.

  19. msb on March 15th, 2009 11:40 am

    from Bakers blog:

    So, what does Zduriencik really think about the 2008 team’s defense? Was it as good as Dewan says? This is important because the team has based a lot of its off-season strategy on upgrading an aspect of the team that — if Dewan is correct — might have needed the least amount of tinkering.

    “I didn’t see it, but from everything I’ve been hearing, there were holes, no question about it,” Zduriencik said.

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