San Diego Chargers : biggest year-to-year improvement/decline

Based on regular season win percentage:

                            Change in 
                              win %
Improvement: 2003 -> 2004     0.500   (0.250 -> 0.750)
Decline:     1999 -> 2000    -0.438   (0.500 -> 0.062)
Last Year:   2015 -> 2016     0.063   (0.250 -> 0.313)