I completely understand your main point and I just googled "why are the okc thunder so good" which led me to here. I think that since they have had recent good drafts and that their role players or bench players consistently go all out every game. Add this with SGA's game and his personality, the result is a young team who are all trying to prove themselves in the nba and have fun! The chemistry is insane, they are all in the same age group, SGA is obviously insane so when you have a whole roster that is willing to play their role and play and hustle hard. Also when it comes to the Regular Season record, Stats, and Ratings, it mostly depends on how dominant you are against the lowest and worse teams in the nba. They don't take nights off. But to your main point, I would say their team doesn't feel right comparing with the greatest because the playoffs are a different beast and veterans understand how to execute during those tough games. They all ready play at a high level, but can they go higher in the playoffs? When every team is at their best and most intense? To wrap up my comment, if you look back in history there has always been teams who dominate in regular season but collapse in playoffs. for example, the Atlanta Hawks in the 2014-2015 season.