Westbrook is overrated. He couldn't win a title with KD, Ibaka, and Harden, and people think he's going to win one with Horford and Smart?
He's not a great shooter. His career FG% is .433/.312
This season it is .424/.343
Compare that to IT's .443/.368 career and .464/383 this season (with similarly limited talent around him)
Take away that massive usage rate and his numbers decline across the board. He doesn't contribute offensively when he's off the ball. It is not a sustainable style of offense.
Durant has made several verbal swipes at Westbrook this season. The fact that he left at all should tell us something about how he regards Westbrook's style.
Their offense is choppy - always has been. The ball does not flow. It is a fatal flaw.
Swap out Westbrook with CP3 on those KD Thunder teams and they win a championship. Westbrook's style hindered them. He is good, but overrated. There is little he could do here to elevate us.
BTW he is also 28, when his athleticism starts slipping in 3-4 years he will be in for a precipitous drop, as his shooting isn't good enough to compensate.