THE BOOK--Playing The Percentages In Baseball

One item Alan may want to look into is the new air conditioning that Chase has been using in the last few years:

http://findarticles.com/p/articles/mi_m0EIN/is_2001_June_7/ai_75350561/

http://www.reuters.com/article/idUS107571+02-Jul-2008+BW20080702

I am not sure if the new cooling system is based off evaporative/swamp cooling or dry heat.  If it is evaporative, the humidity level when the cooling system is running will be different than when the dome is open.

It may be dry heat, but usually dry heat sets a place to a set temperature, but evaporative cooling will have variable temps which the stadium has had since the system was installed.

Re Jeff Z (#1):  The study that Lloyd Smith and I did only looked at the effect of humidity on the ball’s coefficient of restitution (COR).  And that was the focus of the Chase Field article.  We stored the balls in a humidity and temperature controlled environment for at least 2 weeks before doing the measurements.  It takes a long time for things to come into equilibrium.  Short-term changes in the ambient humidity (such as those Jeff was talking about) will not have much of an effect on the COR.  It will affect the flight of the ball, however, but that was not the focus of the study.

We have written a paper on this topic, packaging it together with some corked bat and juiced ball studies we did a few years ago.  The paper will be ready for submission sometime next week and I’ll send Tango a link then.

#2 I looked into Chase after seeing some changes in scoring after moving to this new cooling system, but I don’t know if there was any actual change in humidity so I had to abandon the work.

I was wondering if the new cooling system was increasing the humidity of the balls.  The AC runs for constantly for 3-4 months, so the balls could already be getting the effects of high humidity.

My memory is fuzzy but wasn’t MLB supposed to standardize the storage conditions for baseballs, and every team was going to have a conditioning chamber which would be set to these conditions? 

If each team can tweak the balls MC by choosing it’s own storage conditions that best fits it’s team or for a given pitchers matchup, well, that would explain the increasing importance of HFA (more so if they could control which balls were used by which teams).

Also, if there are no enforceable MLB standards, a systematic strategy could be implemented at a league level and perhaps partly explains the unusual HR jump in the AL last year, and the year of the pitcher in the AL this year after an offseason of listening to the run prevention hype.

Looks like the D-Backs are postponing a decision on using a humidor:
http://www.azcentral.com/sports/diamondbacks/articles/2011/02/03/20110203heat-index-arizona-diamondbacks-humidor.html, pending further study: 

...the club will want to do extensive research on the potential effects of a humidor and to determine the ideal settings (temperature, humidity).