The decision (made easier by giving Westbrook the max) was always between Harden and Ibaka, but what if OKC gave Harden the max instead and shipped Westbrook off for assets far greater than Kevin Martin and Jeremy Lang?
The instant thought is Durant possibly would have stayed in OKC. He and Russ continuously clashed as both tried to assert themselves as the alpha of the team. Harden has shared the spotlight well with Chris Paul in one season in Houston, and could've dealt with the same playing with Durant, who was already set as the franchise player in Oklahoma City. Golden State is still enticing, but having a better rapport with the Robin to your Batman may have been enough to sway KD into signing a new deal.
For everything that makes Russell Westbrook great - an explosive, exciting game, the unwavering will to win - James Harden brings an equally dominant game, plus an underrated intangible: the ability to make everyone around him better. When he's on, he commands so much attention it opens up plays for others. In an MVP season for Harden, the Rockets have been the best three-point shooting team in the league.
The Thunder move as Russell Westbrook moves. His aggressive play can be dominant at times, at others, it becomes more of a detriment to his teammates than an asset.
Westbrook has just one more chance to prove he can take his club to glory. If he doesn't, George is likely to leave him high and dry just as KD did two years ago, the 'what if's' will intensify, and he'll forever have to play through the whispers from fans and pundits who will second-guess every move he makes for the rest of his career.
Harden, on the other hand, is beginning what could be a long run atop the NBA in Houston. Time will tell whether the Rockets will be coronated, but they're much further along (and better) than OKC.
Five and a half years later, Thunder fans have to be thinking in the back of their minds if they could go back in time and trade the other guard.