Detroit Lions : biggest year-to-year improvement/decline

Based on regular season win percentage:

                            Change in 
                              win %
Improvement: 1979 -> 1980     0.438   (0.125 -> 0.563)
Decline:     2000 -> 2001    -0.438   (0.563 -> 0.125)
Last Year:   2024 -> 2025    -0.353   (0.882 -> 0.529)