Biggest declines 

                                           Change in
    All Time:                               win %
  1 Tennessee Titans       1993 -> 1994    -0.625   (0.750 -> 0.125)
  2 Chicago Bears          2001 -> 2002    -0.563   (0.813 -> 0.250)
  3 Atlanta Falcons        1998 -> 1999    -0.562   (0.875 -> 0.313)
  4 San Francisco 49ers    1998 -> 1999    -0.500   (0.750 -> 0.250)
  4 New England Patriots   1980 -> 1981    -0.500   (0.625 -> 0.125)
  4 Denver Broncos         1998 -> 1999    -0.500   (0.875 -> 0.375)
  4 Baltimore Ravens       2006 -> 2007    -0.500   (0.813 -> 0.313)
  8 San Francisco 49ers    1981 -> 1982    -0.479   (0.812 -> 0.333)
  9 New York Giants        1986 -> 1987    -0.475   (0.875 -> 0.400)
 10 Tampa Bay Buccaneers   2005 -> 2006    -0.438   (0.688 -> 0.250)
 10 San Diego Chargers     1999 -> 2000    -0.438   (0.500 -> 0.062)
 10 Philadelphia Eagles    2004 -> 2005    -0.438   (0.813 -> 0.375)
 10 Oakland Raiders        2002 -> 2003    -0.438   (0.688 -> 0.250)
 10 New Orleans Saints     1979 -> 1980    -0.438   (0.500 -> 0.062)
 10 Detroit Lions          2000 -> 2001    -0.438   (0.563 -> 0.125)
 10 Detroit Lions          1991 -> 1992    -0.438   (0.750 -> 0.312)
 17 Tennessee Titans       2003 -> 2004    -0.437   (0.750 -> 0.313)
 17 St. Louis Rams         2001 -> 2002    -0.437   (0.875 -> 0.438)
 17 Jacksonville Jaguars   1999 -> 2000    -0.437   (0.875 -> 0.438)
 20 Tampa Bay Buccaneers   1982 -> 1983    -0.431   (0.556 -> 0.125)
 21 Chicago Bears          1968 -> 1969    -0.429   (0.500 -> 0.071)
 21 Atlanta Falcons        1973 -> 1974    -0.429   (0.643 -> 0.214)
 23 New York Jets          1969 -> 1970    -0.428   (0.714 -> 0.286)
 23 Buffalo Bills          1975 -> 1976    -0.428   (0.571 -> 0.143)
 25 Cleveland Browns       1989 -> 1990    -0.406   (0.594 -> 0.188)

    Last season:
    Baltimore Ravens       2006 -> 2007    -0.500   (0.813 -> 0.313)
    New York Jets          2006 -> 2007    -0.375   (0.625 -> 0.250)
    Chicago Bears          2006 -> 2007    -0.375   (0.813 -> 0.438)
    Kansas City Chiefs     2006 -> 2007    -0.313   (0.563 -> 0.250)
    St. Louis Rams         2006 -> 2007    -0.312   (0.500 -> 0.188)
    Miami Dolphins         2006 -> 2007    -0.312   (0.375 -> 0.063)
    Atlanta Falcons        2006 -> 2007    -0.188   (0.438 -> 0.250)
    San Diego Chargers     2006 -> 2007    -0.187   (0.875 -> 0.688)
    New Orleans Saints     2006 -> 2007    -0.187   (0.625 -> 0.438)
    Philadelphia Eagles    2006 -> 2007    -0.125   (0.625 -> 0.500)
    Denver Broncos         2006 -> 2007    -0.125   (0.563 -> 0.438)
    San Francisco 49ers    2006 -> 2007    -0.119   (0.432 -> 0.313)
    Cincinnati Bengals     2006 -> 2007    -0.062   (0.500 -> 0.438)
    Carolina Panthers      2006 -> 2007    -0.062   (0.500 -> 0.438)