So I got started here explicating some advanced methods of analyzing player performance. I think that the article on DIPS, while somewhat dense, made a strong case for the amount of luck that gets captured in an ERA. Over the next week-ish, I'm going to hand calculate the DIPS for our starting pitchers to see how much luck may or may not have had a hand in our less than stellar rotation this season. However, before I do this (actually because this will take me such a good chunk of time) I wanted to turn this into a series of sorts.
As much as I understand and can know that the BABIP/ERA phenomenon is statistically valid and often empirically sound, there has always been a part of me that's wanted to call B/S. I'm going to run with that thought until I finish cranking out the numbers and we'll see of some of the other measures I look to can support or cast doubt on what the DIPS-ERA differentials may or may not be.
Today I'm going to roll with a BP Statistic "Quality of Batter Faced." It looks at the combined BA, OBP, SLG, and OPS of every batter a pitcher has faced. It can be used a barometer, of sorts, to see whether a pitcher's performance has been legitimate or whether it's the happenstance of facing superb or poor hitting.
Are the results surprising to anybody else? Roy has faced the second easiest offense and he had struggled for so long. My theory, when the hip flared up, was that he was quietly struggling with it all season long -- which his post injury performance I think bolsters that idea. I'd love to see his pre and post ASB LOB% to see if his out of the stretch pitching is what was hurting him. But I'm digressing. Looking at these numbers, Brian Moheler seems to have posted some very legitimate performances, where as one has to keep scratching their head at the Randy Wolf acquisition. We could consider cutting Wandy some slack and I think it's high time we show Brandon Backe the way to Round Rock.
While I'm not sure of the overall validity of this measure, it's some food for thought. It'll definitely be something to consider when we look at the DIPS-ERA differentials on our starters. Perhaps we'll see that Roy has pitched much better than his ERA suggests, but we can also couch that in the context of his quality of batter's faced or vice versa for any of the pitchers above.
**For some context on the numbers, Roy's batter-faced line from last year was: .260/.332/.410/.742. Wandy: .259/.327/.412/.739. Also the toughest line for pitcher faced in 2008 (min. 100 IP), belongs to Matt Garza: .269/.340/.425/.765. The easiest belongs to Adam Eaton: .250/.321/.388/.709. FYI, Randy Wolf owns the 8th easiest line...iiiiiiisssshhhhh**