How much do you really value defense?

Here’s the situation: you’re the GM of a well-balanced team heading into the 2008 baseball season. You have adequate pitching, defense, and hitting, and all you are now looking to do is round out your team by acquiring a right fielder. Two are available for you, and we’ll assume that both are the same age, will cost the same price monetarily, and have the same durability. Also, by the way of some awesome forecaster you are 100% sure that this will be their offensive numbers for the upcoming season:

Player A: .283/.381/.498, .379 wOBA

Player B: .249/.323/.406, .321 wOBA

Now, here are their defensive numbers for the upcoming season, again with 100% certainty:

Player A: -46.6 UZR/150

Player B: -10.5 UZR/150

Finally, here are their respective WAR totals for the year, again with certainty, and this time revealing their identities:

Brad Hawpe: -.7 WAR

Jeremy Hermida: .1 WAR

To stick with the situation we were given, we are really only concerned with finding the best right fielder possible for the 2008 season (let’s forget long-term goals). To sum it up, Hawpe is good offensively, but is in another league in terms of his miserable defense, which gave him negative value. Hermida is pedestrian offensively, and has pretty bad defense as well, but does just enough on both ends to give him at least some positive value.

So the question you now have is: how much do you really value defense? Let’s remember that UZR is not a rate stat; it is specifically telling us that Brad Hawpe will cost his team -46.6 runs (~4.7 wins) thanks to his defense, whereas Hermida will cost his team -10.5 runs (~1 win) thanks to his. Can we fudge these numbers? Maybe, but probably not by much. MGL gives us two types of measurement errors, but for our purposes only the second one applies:

In the case of defensive metrics we have large and numerous measurement error. For example, that one ball that Yuni got to that is only gotten to 20% of the time by the average fielder, may NOT have had the characteristics we thought it did. While all hard hit ground balls hit in area X up the middle may be fielded 20% of the time, there are obviously lots of different types of balls in that bucket, from an easy, high chopper (albeit hard hit, if that is our bucket) to a ground skinner. As well, some of those balls in that bucket are hit directly up the middle and some are hit a little to the SS or 2B side. In addition to that, sometimes the SS is playing in position A and sometimes in position B because of the batter, pitcher, base runners and outs. Lot and lots of potential measurement error. So that ball that Yuni fielded may have been an easy chopper a little towards the SS side, even though it went into the “hard hit ball up the middle” bucket which is only fielded 20% of the time on the average by all SS.

I think this question is ultimately very similar to the post Dave Cameron made at Fangraphs when he compared Adam Dunn to Nyjer Morgan. However, the difference here is that Hermida isn’t some defensive superstar; he’s actually very bad himself. But when we’re talking about a significant difference in offensive value, how much weight do we put into the defensive difference when both are bad themselves? I ultimately think that it doesn’t really matter if both are “good” or “bad;” we have the data, and the data clearly shows us just how much better/worse one player is than the other. However, John Dewan, of “The Fielding Bible” and Plus/Minus fame, recently said that:

On offense I believe we’re measuring 80-90 percent of the true ability of players. On defense, I believe we’re at about the 60 percent level. But we’re still at the tip of the iceberg in terms of precision and a ton more can be done, especially defensively. As new forms of data become available, we’ll be able to enhance our defensive systems. One example: BIS has now developed a batted ball timer, which we believe will greatly improve the accuracy of our system.

If we’re going to take this at face value, we then may be more inclined to take Hawpe, as we are more confident in accuracy of the offensive stats compared to the defensive ones. But then again, the difference between Hawpe and Hermida’s defense was so huge than even making some changes based on possible measurement error/inherent problems with the system might not be enough to put Hawpe over the top.

I think Rob Neyer summed up the frustration/hope involved in defensive metrics best when he said, “Maybe we don’t completely get the value of defense yet. But trust me, Dave Cameron: we’re getting there, and we’re getting there quickly.” I hope (and think) that he’s right, because I’m still not fully sold on which player I’d take. I’m leaning towards Hermida (barely), but I’d still like to hear from others.

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  1. Steve Stein said...

    I follow your argument except for this: “we’ll assume that both will cost the same price monetarily”.

    My guess is that better offense = higher salary, pretty much, and that Hawpe will cost you more, maybe much more, than Hermida.

    This may make it wiser to lean towards Hermida, at least until defense is properly compensated in relation to offense.

  2. Pat Andriola said...


    I was just saying that, for the sake of the argument, that we’ll pretend that they cost the same amount.

    Hope that clears things up.

  3. Steve Stein said...

    Yes, Pat I get that.  I’m just saying that this will never be the case in reality (as currently constituted in the baseball salary structure), so it’s not a real argument.  In reality, Hawpe costs 3 times as much, no?

    Plus I’m gobsmacked – is Hawpe REALLY that bad?  46 runs?  Wow.  How bad is Manny, then?

    Your analysis has real value for simulation leagues like mine, where players really do cost the same.  An analysis of how fielding is simulated can lead to a real valuation of defense, and savvy managers can use this information to their advantage.

  4. Dan Novick said...

    Hawpe is better than that. I know his UZR numbers suck (the past few years), but as you said there’s a ton of measurement error. After all, if he’s that bad now, how do you explain his +2 from 2006 in 150 games?

    If he actually was THAT bad, the Rockies would have noticed and done something about it by now, even if they don’t look at defensive stats. It might have something to do with Coors, since Dexter Fowler has a pretty terrible UZR in center field, despite having a reputation for good defense in the minor leagues (IIRC).

    If I had to put money on it (which I can’t because there’s no way to ever know his TRUE fielding talent), I’d say he’s between 15 and 25 runs below average over a full season.

  5. Slugger O'Toole said...

    I would lean towards Hawpe in most cases as I think that his defense may be bad, but it is hard to believe that it is bad enough to cost 5 games of WAR. It is a very situation based desicion though. If your team is hurting for runs and has alot of groundball heavy pitchers, Hawpe would hurt you less and therefore have more value. On the flip, if you put him in Petco or Safeco where hsi weaknesses would be exposed, he would be a disaster.

    I agree with Steve though, that the value given to Hawpe will be significantly higher than that given to Hermida so in reality Hermida is a much better deal. I wonder if the Red Sox fail to sign Jason Bay, would they pursue Hawpe for left? That seems like a perfect fit. Fenway’s left field is a perfect spot for a crappy outfielder.

  6. Pat Andriola said...

    I agree, Dan, that he’s not really “that” bad. It’s probably a combination of bad defense + bad luck +Coors Field+ measurement errors that drove his defense to be -46.6. I also think his “true talent” is much better than that (and I’d much rather have Hawpe on my team than Hermida overall) . However, I think if you just look at 2008 performance (i.e. who was “better?”) than it’s a much tricker question.

  7. devil_fingers said...

    Shouldn’t the question also be whether you’re in the AL or NL? At a certain point, in the AL, at least, you have to cap the defensive projection+positional adjustment at, say, -22.5 (the DH adjustment if the player hasn’t DHed extensively before).

    An AL team could put Hawpe at DH.

    IN the NL, you could also try a player like Hawpe at 1B, but that’s another issue.

    Hawpe is a particular favorite of mine. See

  8. Pat Andriola said...


    Yes, this would be an NL team, so you couldn’t put your pick at DH.

    However, I wouldn’t say you couldn’t move Hawpe, but I asked to assume your other positions are filled.

  9. razor said...

    Hawpe actually has hit more HR’s in his career away from Coors and his overall career line is pretty close home and road. His UZR has been terrible the last few years and although he’s certainly not strong defensively, there is absolutely no way he’s as bad as UZR makes him out to be. This isn’t even close. Hawpe by a landslide.

    UZR had Yunel Escobar as just barely above league average last year at SS as well and the plus/minus system had him #1 in the league until the last week of the season when Rollins went by him. This year UZR has Escobar actually below average defensively. All I can say from watching an ton of games that if that’s correct, I must be missing a ton of great defensive SS’s playing in the NL. Anyone know Escobar’s plus/minus this year? Something here doesn’t make too much sense…

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