A word about DER

by shoewizard on May 19, 2008 12:48 PM EDT Comment 16 comments

The simple act of turning balls in play into outs. Simple, easy, clean concept.

Jonah Keri wrote the following in the NY Sun today in a review of the success the Florida teams are having this year:

PECOTA saw the Rays making their biggest improvement on defense. In acquiring slick-fielding Jason Bartlett to replace the mishmash of Brendan Harris, Ben Zobrist, and company, the Rays found a big upgrade at the most important position on the diamond. Evan Longoria has been a big upgrade at third base, moving Akinori Iwamura over to second, where he's become a bigger defensive asset. Subtracting Delmon Young from the outfield has also helped.

Indeed, much of Tampa's perceived pitching problems last year were actually the result of their defense failing to turn balls in play into outs. Last year, the Rays were dead last in the majors in that category (also known as Defensive Efficiency), converting just 66.2% of balls in play into outs. It should have been no surprise, then, to see Tampa post the worst team ERA last year, at 5.53. The Rays' starters were the third-worst group in the game at 5.20; the bullpen was the worst in baseball by a wide margin, at 6.16.

This season, the Rays have jumped to second in Defensive Efficiency, at 72.5%. It's no surprise that their run prevention has also improved dramatically — a 3.68 team ERA, fifth-best in the majors.

NY Sun Article

I really don't think that anyone would dispute that having athletic fielders that can make plays helps out a teams pitchers. It's great to have a high team fielding percentage, but if the fielders have the range of fire hydrants, it doesn't really do that much good to make few errors if you are letting too many other balls go for hits.

Of course the ideal situation is for a team to have a high DER and also have a good fielding percentage. I don't advocate looking at only one stat. I'm just saying that in looking at a team's overall defense, you need to look at BOTH DER and Fldg. % if you want to get a fuller, clearer picture.

Finally, I will leave with this little chart, and leave it for the reader to determine which number seems to correlate more closely to improvement in ERA

Year	ERA	DER	Fld %
2004	4.95	0.681	0.977
2005	4.84	0.683	0.985
2006	4.48	0.685	0.983
2007	4.13	0.690	0.983
2008	3.56	0.710	0.982

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Heard your name mentioned by Sut last night when they were talking about DER.

The ERA/DER correlation seemed obvious when they mentioned what it measured. Of course if you have a staff that allows fewer hits, a higher percentage of BIP will be outs, regardless of what your D is doing behind them. I’m wondering if it is even more closely related to WHIP, can you add that line?

by manphibian on May 19, 2008 1:23 PM EDT reply actions 0 recs

Pitchers control over balls in play

Statistical research has shown that the effect that pitchers have over their BABIP against, (Batting avg on balls in play, which is the inverse of DER of course) is not nearly as great as most people probably think. The effect is not zero of course, but it’s really not as great as you might think.

Comparing WHIP doesn’t answer this question for you, because the H component of WHIP is of course hits, and the point is that a good defense helps reduce the amount of hits the pitchers give up, thereby reducing their ERA. So of course if the DER is high, the WHIP will come down, and the ERA then goes down with the WHIP. (unless the pitchers are walking more guys than usual),

Team WHIP for the 5 year period above

2004: 1.50
2005: 1.45
2006: 1.40
2007: 1.38
2008: 1.23

Of course if you go look in detail, you will see that the walk rates are down SUBSTANTIALLY.
The current team ERA is a combination of a bunch of strike throwers not walking guys, getting a fair amount of strikeouts, (limiting balls in play in the first place), not giving up many homers, AND, when the ball is put into the player, the defense is turning those BIP into outs at one of the highest rates in the league.

The TOTAL result is of course a low ERA.

by shoewizard on May 19, 2008 1:51 PM EDT up reply actions 0 recs

I still think DER is more indicative of the quality of your pitching staff than the quality of your defense. Of course the two have a lot to do with each other, so it may be splitting hairs

by manphibian on May 19, 2008 2:43 PM EDT up reply actions 0 recs

"I really don't think that anyone would dispute that having athletic fielders that can make plays helps out a teams pitchers."

I can think of at least one guy in this team’s broadcasting booth that might take umbrage with it…

by dahlian on May 19, 2008 1:39 PM EDT reply actions 0 recs

The one that spits?

You can stand under my umbrella

by unnamedDBacksfan on May 19, 2008 1:51 PM EDT up reply actions 0 recs

What was once a discussion on DER during yesterday’s game became Gracie’s metamorphosis into Grandpa Simpson…I kept waiting to hear how ballplayers in Gracie’s era tied onions to their belts, which was the style at that time….

by IndyDBack on May 19, 2008 1:53 PM EDT up reply actions 0 recs

Oh thats not true at all

Grace has a very keen appreciation for athletic defensive play. He talks about the athleticism of the fielders all the time. He just likes to tease Daron for being a stat geek, and may not fully appreciate DER’s ability to help us get a handle on a team’s range and ability to turn BIP into outs.

by shoewizard on May 19, 2008 1:54 PM EDT up reply actions 0 recs

And he likes to wail on his statistical punching bags

of holds and quality starts to dismiss all “stats geeks” in general.

I have no more faith in Gracie’s ability to use DER to evaluate a team’s defensive effectiveness than I do for him to evaluate a pitcher’s performance using anything other than wins and ERA. With pitching he may every now and then talk about the importance of not walking guys or getting a big strikeout, but at the end of the day those are just stats – they don’t tell you anything about whether a ballplayer is a winner. Remember, this is the guy that wouldn’t accept any criticism about Randy’s 6 IP, 4 ER, 6 Hit, 3 BB, 2 HR start being anything less than good.

Of course he likes athletic fielders, but he’s never said anything to make me believe that he would think a slightly error-prone player with a bitchin’ RZR would be better than a sure-handed Derek Jeter-type in the field.

And if you really do believe in something, but go on to mock its verity in a public forum, well, I don’t often go throwing around phrase like worse than hitler, but…

by dahlian on May 19, 2008 2:21 PM EDT up reply actions 0 recs

My favorite part of his ranting last night was when he was talking about “Give me the guy who hits when it counts etc., not the guy who hits his HRs when up/down 8” or something along those lines, saying stats couldn’t show that. If I’m not mistaken, there are a number of “clutch hitting” stats, and from what I’ve heard they show us that it isn’t really repeatable/projectable.

by manphibian on May 19, 2008 2:37 PM EDT up reply actions 0 recs

Ding ding ding!

Godwin’s Law! Dahlian is our winner. Took a week, though.

Max Scherzer is all out of bubblegum.

by DbacksSkins on May 19, 2008 2:54 PM EDT up reply actions 0 recs

I've always found

That invoking Godwin’s law is just a cheap device to try to get the last word. ;)

by shoewizard on May 19, 2008 3:26 PM EDT up reply actions 0 recs

Invoking it?

Or confirming it?

Max Scherzer is all out of bubblegum.

by DbacksSkins on May 19, 2008 3:47 PM EDT up reply actions 0 recs

I don't think you can invoke Godwin's Law

when the post in question is clearly meant to be in parody of it.

by dahlian on May 19, 2008 4:09 PM EDT up reply actions 0 recs

Well, not in any argumentative sense, thus, not fulfilling Godwin's associated corollaries.

But then again, like last time, I’m not an active participant in this debate anyway.

Max Scherzer is all out of bubblegum.

by DbacksSkins on May 19, 2008 4:54 PM EDT up reply actions 0 recs

Good stuff

A couple of points come to mind. It’s difficult to compare DER across teams, because it’s not a park-adjusted figure. Obviously, a defense that plays in a bandbox is going to have an easier time converting balls into outs, than one which has to patrol the cavernous wastes such as Petco. In general, I guess, hitter-friendly parks would tend to produce lower DERs – which makes Arizona’s good figure, even more impressive.

As noted elsewhere, I am also curious how double-plays factor into things. I would presume a team which turns a lot of double-plays would have a lower DER, simply because they allow more runners on base. For example, take two identical at-bats. The first is a bloop which Team A catches, but Team B lets fall for a single. The second is a ground-ball to the second baseman – in both cases it results in an out, but with Team B having a runner on first, they turn the double play. Team A has a DER of 100%, having converted both balls into outs, but Team B has a DER of 50%: the net result, however, is exactly the same, two down and the bases empty.

Like any other statistic, it’s a tool, and should be used with the usual warnings and caveats that apply to such things. But taken in conjunction with other figures, it’s probably very useful. What I particularly like about it, is that’s a lot more objective than “errors”, since it’s based simply on whether the batter is out or not. Assigning blame for a failure is not any part of the equation.

by Jim McLennan on May 19, 2008 11:16 PM EDT reply actions 0 recs

Paul Depodesta says about Petco:

However, in an earlier posting we established that Petco Park isn’t batting average friendly. Furthermore, the Park is as tough on doubles as it has been on home runs. The fact of the matter is that despite the dimensions of the ballpark, fly balls go to die in Petco, which is also why defense in CF may not be quite as important as it would initially appear. I guess we can blame the perfect weather in San Diego.

That surprised me. But it makes sense.

by shoewizard on May 20, 2008 12:06 AM EDT reply actions 0 recs