Refinements in SFR

With all the Mitchell report goings on today I almost forgot that my column on Baseball Prospectus this week focuses on refinements of the SFR (Simple Fielding Runs) system I discussed last week. In particular it focuses on adding the additional context of batter handedness and bunting as well as a more sophisticated technique for partitioning ground balls among shared "areas of responsibility".

After the article was submitted, however, I realized that on the latter point there is a simple way to partition balls between the short and second area of responsibility following the same principle outlined in the column instead of making a 50/50 split as I did. I've since incorporated that and will be taking a look at whether it improves the system for middle infielders. In any case, as always comments are welcome.