The OKC team isn't really a failure at all. They just aren't as good as casual onlookers believe they should be. They are a perfect example that "fit" and "chemistry" matter in the NBA. A lot of fans believe that you should just throw big name talent together a coach should just work it out.
It also shows you that some "stars" become worse than role players when they are required to be role players and also elite players have to be able to play w/o the ball to win. Melo just can't play a simple role offensively on a team. His style of play will always rear it's ugly head at times that hurt the team. Westbrook is ineffective on the floor without the ball. All of these things limit the offense, especially in the playoffs. This is one reason why Lebron is still an issue without the rock and Westbrook isn't. One is always a threat.