Over at THT, there's an article about the current state of defensive analysis in reaction to a post by Buster Olney which was also quoted here. Here's the article: http://www.hardballtimes.com/main/ar...cating-buster/
One of things I love about it is the chart used about 2/3 of the way down. In my mind it's brilliant -- Edward Tufte would be proud. Anyways, check it out -- especially those looking for some more background on defensive stats.