Analysts most often bring up Serge Ibaka and more importantly his contract, as the reason the Thunder had to move James Harden. Ibaka though plays an entirely different position than Harden. Every championship level team needs a rim protector as the last line of defense such as Ibaka. The person the Thunder really chose over Harden was Russell Westbrook.
So did the Thunder make the right choice?
Whenever committing yourself to a franchise cornerstone, you always want a player who can stay on the court. Westbrook has never missed a game in his entire five year career. Harden missed six games due to a hamstring injury during his rookie season, but hasn't missed a game since. They are virtual twins in this category. Both appear to be carved from granite.
Edge: Big for Westbrook
According to Basketball-Reference.com they are equal on the defensive glass with Harden averaging 4.0 RPG to Westbrook's 3.8 RPG. Also nearly identical in SPG with Harden averaging 1.9 SPG to Westbrook's 1.8 SPG. Blocks gives no separation either with .04 to 0.3 respectively for Harden and Westbrook. Westbrook edges Harden in Defensive rating which is an estimate of points allowed per 100 possessions with 104 to Harden's 107. The only large discrepancy is in Defensive win shares which is an estimate of wins contributed to the player due to his defense. Westbrook has contributed 3.2 wins this year to Harden's 2.3, nearly a full win more.
Harden has a sizable advantage in PPG with 26.3 to Westbrook's 23.4. Westbrook though has the better APG with 7.5 to Harden's 5.9, but that difference could be contributed solely to the presence of the league’s best scorer in Kevin Durant. Harden is the best at getting to the free throw line in the entire league with a league high 10.2 FTA per game. Westbrook ranks sixth in the league at 7.0 FTA. Yet, would have to increase his attempts by 45.7% to equal Harden, that's quite a bit. Harden shoots .449 FG% over 17.0 FGA to Westbrook's .437 FG% over 18.9 FGA. From the three point line the disparity is larger as Harden shoots .374 to Westbrook's .323, also Harden shoots 6.0 threes per game to Westbrook's 3.7. Harden makes more threes and takes more threes. The advanced metrics don't help Westbrook's case either. Harden's true shooting percentage (TS%) which takes into account 2-point field goals, 3-point field goals and free throws. Harden's TS% is .611 to Westbrook's .531. Their effective field goal percentage (eFG%) which takes into account that 3-point shots are worth one point than 2-point shots, also favors Harden .515% to Westbrooks .469%. All these stats are shown in the offensive win shares as Harden has 9.3 to Westbrook's 6.5. Harden beats Westbrook in nearly every category even though Westbrook's usage rate of 32.4% is higher than Harden's 28.7%.
Edge: Big for Harden
Westbrook wins in athleticism and defense. Harden in offense and a push in durability. The thing that separates these two most to me, and why the Thunder should have kept Harden over Westbrook is mentality. Westbrook's mid game temper tantrums and spats with media members have shown he is volatile and immature. Harden never spoke out about his sixth man role with the Thunder and seamlessly became the Rockets leader despite arriving just before the start of the season. Harden is the type of man that lets his actions speak for him. He is the type of guy everyone wants in their locker room. If I was Sam Presti I would have had kept Harden and shopped Westbrook. The crazy thing also is the Thunder definitely could have gotten more in return for Westbrook as well. Daryl Morey is happy and that is an understatement, Harden is in Houston. Westbrook is phenomenal talent but Harden is better suited for winning championships.