Line Drives, BABIP, and Minute Maid Park

post from The Crawfish Boxes on 08 January 2009 12:21:00 AM. © The Crawfish Boxes

Here is an interesting article at Fangraphs which touches on all of the subjects in the title of this post. The author demonstrates that line drive rates and Batting Average on Balls in Play (BABIP) vary by ballpark. The article questions the validity of comparing the "Line Drive % + .12" rule of thumb to BABIP rates. However, in the course of doing so, the article identifies significant differences in line drive rates by ballpark.

This, in itself, is intriguing. And Minute Maid Park is at ground zero of this phenomona. As stated in the article:

Four of the lowest six LD rates belong to Michael Bourn, Geoff Blum, Ty Wigginton and Hunter Pence, and Minute Maid Park has the second lowest LD park factor at 0.82. This is not saying that Houston batters hit fewer line drives - it’s that Houston and it opponents both have 18% fewer balls scored as liners in Houston than they do on the road.

Why? Well that is the intrigue I mentioned. Could this amount to human bias in the coding of batted balls as line drive, flyball, etc. ? Are factors like the batting background, atmospheric conditions, foul territory, and the like causing differences among ballparks?

In some previous posts regarding Hunter Pence, I expressed concern about his seemingly depressed line drive rate this year. Now I see that maybe this has as much to do with the ballpark as it does Pence's skill.

The article derives a simple linear equation using line drive, flyball, and groundball rates as variables which proves to be very accurate at predicting hitters' BABIP. However, when the formula is turned around to predict pitchers' BABIP, he finds that certain pitchers consistently beat the prediction:

Even so, some pitchers consistently defy the estimates. Roger Clemens, Brian Bannister, Chien-Ming Wang, Carlos Zambrano, Dan Haren, Brandon Webb, Chris Young and Greg Maddux all do at least .020 better than estimated. On the other end, Zach Duke, Sidney Ponson and Glendon Rusch all under perform by at least .020. Is it the ballpark? Is it their defense? The batters they faced? Or is it their own skill or lack of it?

The author of this article seems to be finding that the normally accepted precepts of DIPS are more nuanced than it is often presented. He hopes to present more detailed research in the future which disaggregates batted ball types and fielding conditons by ballpark in more detail.

This may or may not totally bore you. The article is somewat dense to read. But I have to say that this article seems to be challenging accepted views on BABIP and DIPS in an interesting way.

Read The Full Article:
http://www.crawfishboxes.com/2009/1/7/713575/line-drives-babip-and-minu