Carolina Panthers : biggest year-to-year improvement/decline

Based on regular season win percentage:

                            Change in 
                              win %
Improvement: 2014 -> 2015     0.469   (0.469 -> 0.938)
Decline:     2015 -> 2016    -0.563   (0.938 -> 0.375)
Last Year:   2024 -> 2025     0.177   (0.294 -> 0.471)