Friday, October 7, 2011
Before the 2010 season, I got familiar with the idea of regression to the mean. This concept illustrates the phenomenon of an outlying statistic in one season (such as an extraordinary ERA) coming back down to earth in the next, simply by chance.
My study examined how the best pitchers (in terms of ERA) fared in the following season, dating back to 2000. To measure this, I (somewhat arbitrarily) choose 2.50 as the cutoff for ERA.
Here’s what I found…