Six years ago, Football Outsiders ran a guest column by a reader named Andreas Shepard featuring a system for historical estimates of our DVOA metrics. Shepard used standard stats to estimate DVOA going all the way back to the NFL-AAFC merger in 1950 so that we could run cool tables with the best and worst teams in modern NFL history without being limited by the years for which we had collected play-by-play data.
Since that article first ran, we've added ten more years of play-by-play breakdowns to our DVOA database. Our historical collection of play-by-play now goes all the way back to 1985 but we've also added the last six years in the NFL, featuring some great regular-season teams and units including the 2019 Baltimore Ravens, the 2018 Kansas City Chiefs offense, and the 2015 Denver Broncos defense.