2003 power surge

That was the year of the "Rabbit Ball." Please have a look at this thread and Albright-san's research accompanying it.

Very interesting thread - again, many thanks. Is there any validity to the rabbit ball theory?

For now, I will avoid using 2003 in my sample.

Ben

Mizuno ball (baseball fans called the rabbit ball) had been used in the Pacific league since 2001.

There were a number of studies done on it at the time, and the general conclusion was the the Mizuno ball had more jump to it than the other balls.

This was so well known that some teams would use the Mizuno ball against some opponents but not against others (depending on the overall opposing team power). From what I understand, the only thing the home team had to do was provide sample balls to the visiting team before the series (for practice) to have that maker's ball used. There were talks of changing this policy due to this abuse, but I never heard of any resolution.

This whole issue did seem to disappear shortly after all of the articles pointing to the Mizuno ball as having more jump than the others (despite still being within specification). I don't know if Mizuno changed their manufacturing technique to fall in line with other ball manufacturers, if the teams stopped using the Mizuno balls, or if Mizuno's PR department threatened to pull advertisements if they saw any more of these articles. But the rabbit-ball era came to an abrupt end soon after.

I found this:

8 Teams to use New Mizuno Ball in 2005 Season [Japan Ball]

Thought it might be of some help. Drats - this means I've only got one year of data.