Great question -- Buffalo led the league this year at 36.2%, and they would have been below the all-time SB average if they'd made it. Baltimore was 25.2%, which is in between KC and SF, and Detroit was at 17.0%, which would have ranked 9th-lowest of any Super Bowl team ever. (Fascinatingly, the 2019 Niners were actually the lowest in SB history -- only 9.1% of their AV came from players on the 2015 roster.)
So we're clearly in an era of low continuity overall, although the thing that sets the Niners and Chiefs apart is that they had both gone to the Super Bowl 4 years earlier, which tends to be correlated with a team having more continuity. (Good teams usually churn their rosters less than bad ones, etc.)
For 2023, is any team's returning share much higher than KAN or SFO? e.g. What would it have been for BAL or DET - I imagine similar?
Great question -- Buffalo led the league this year at 36.2%, and they would have been below the all-time SB average if they'd made it. Baltimore was 25.2%, which is in between KC and SF, and Detroit was at 17.0%, which would have ranked 9th-lowest of any Super Bowl team ever. (Fascinatingly, the 2019 Niners were actually the lowest in SB history -- only 9.1% of their AV came from players on the 2015 roster.)
So we're clearly in an era of low continuity overall, although the thing that sets the Niners and Chiefs apart is that they had both gone to the Super Bowl 4 years earlier, which tends to be correlated with a team having more continuity. (Good teams usually churn their rosters less than bad ones, etc.)