Leading into free agency this season, we introduced the Improvement Index, which tracks player movements this offseason and quantifies the change in teams’ collective WAR (wins above replacement) based on PFF’s research and modeling. The details of the Improvement Index can be found here. The simple way of thinking about the number is the percentage change in cumulative player WAR projected for 2020 from end-of-year 2019 rosters to now.
The most recent Improvement Index can be found below, with the New England Patriots in last place after losing, most notably, quarterback Tom Brady and replacing him with Brian Hoyer.