Dont know if this has already been discussed or not, but recently ESPN AFC South Blog shared a link to PFF's Free Agency Tracker. Does anyone know how they arrive at their ratings? Byrd tops their list at +23.7, and Moore is 4th at +6.7. Chung also grades out slightly positive at +1.4. Interesting that Ed Reed grades out negative. On a side note, it looks like there are some higly rated UFA DT & DE out there who are relatively young and not well known.