Portland Trail Blazers biggest year-to-year improvement/decline
based on regular season win percentage:

                            Change in 
                              win %
Improvement: 1989 -> 1990     0.244   (0.476 -> 0.720)
Decline:     2004 -> 2005    -0.171   (0.500 -> 0.329)
Last Year:   2007 -> 2008     0.110   (0.390 -> 0.500)