I would say they have paid their dues just on an abbreviated schedule. The run through the playoffs this year is pretty crazy.
Durant rookie year with Sonics was 20-62
2008-2009 1st year: 23-59 including starting 1-13 (Firing PJ Carlisimo) and going 3-29 through the first 32 games. They finished the last 50 going 20-30. They went from not being remotely competitive to being very competitive in most games.
2009-2010 2nd year: 50-32 playoff birth as an 8 seed (The West was so good). 1 Pau Gasol block out away from extending the series to 7 games against the eventual champ Lakers in the first round of the playoffs.
2010-2011 3rd year: 55-27, 4th seed in the playoffs. Beat Denver 4-1, Fought like hell to beat Memphis in 7 including a bat shit crazy 3 overtime game 6. Lost to Dallas 4-1 in Western Conference finals after giving up multiple 4th quarter leads.
2011-2012 4th year: abbreviated season 47-19 2nd seed playoffs, swept defending champ Dallas 4-0, beat Lakers 4-1, backside sweep of 20 win streak Spurs to win West finals 4-2. Finals birth.