Former Oklahoma City Thunder teammates James Harden and Russell Westbrook are threatening the record books this season in similar ways. Westbrook is bidding to become the second player in NBA history to average a triple-double, while Harden has an outside chance to join Nate "Tiny" Archibald as the second player to lead the league in both scoring and assists, should Westbrook's points per game slip.
Looking at their value to their teams, who is having the stronger offensive season?
A case can be made for both superstar guards.
The case for Westbrook: Unprecedented shot creation
A few years ago, Milwaukee Bucks director of basketball research Seth Partnow developed the concept of "true usage" on Nylon Calculus, crediting players for their playmaking as well as the plays they finish with a shot, trip to the free throw line or turnover.
Partnow's measure relied on potential assists as tracked by SportVU, meaning it can't be calculated before the advent of camera tracking. So let's instead consider what we might call "combined usage" -- a player's usage rate added to his actual assists per 100 team plays. This can be calculated back to 1977-78, the first season the NBA recorded individual turnovers. In that four-decade span, nobody has ever accounted for more than half their team's offense while on the court ... until Westbrook this season.
On its own, Westbrook's 42.4-percent usage rate is already the highest in recorded NBA history, smashing the 39.0 percent of the Lakers' plays Kobe Bryant used during 2005-06. But Bryant's assist rate was far lower as a shooting guard, so Westbrook already held the combined usage record with his 2014-15 campaign.
Now Westbrook is blowing that mark out of the water by either finishing or assisting on 55.6 percent of the Thunder's plays. Even though Harden's combined usage this season is the third-highest on record, Westbrook's edge is still larger than the gap between Harden and the player ranked sixth in the category this season, LeBron James.
When we account for potential assists as Partnow originally did, Westbrook's true usage is more than two-thirds of Oklahoma City's plays (66.9 percent, to be exact). There's no such thing as a one-man offense in basketball, and of course somebody has to be on the receiving end of those passes, but Westbrook is coming as close as we've seen in modern NBA history.
It's no surprise, then, that the Thunder offense has collapsed without Westbrook. When he plays, Oklahoma City has averaged 107.4 points per 100 possessions, which would rank eighth in the NBA this season. When Westbrook sits, the Thunder's offensive rating drops to 97.1, which would be last in the league -- 1.5 points per 100 possessions fewer than the Philadelphia 76ers manage.
The case for Harden: Rare efficiency given role
There are two primary components of offensive value, and while Westbrook has Harden beat on shot creation, Harden has a big edge in the other: efficiency. Viewed in that context, Harden's season has been nearly as remarkable.
While there have been players like Westbrook who have posted higher usage rates, and those who have posted better true shooting percentages (which measures points scored per shot or trip to the free-throw line), nobody in recorded NBA history has surpassed Harden in both categories.
Among players who have used at least a third of their team's plays while on the court, Harden's .614 true shooting in 2016-17 ranks No. 1 ahead of prime seasons from Michael Jordan and James ... and Isaiah Thomas this year.
Westbrook ranks last in true shooting among the five players who qualify this season (DeMarcus Cousins and DeMar DeRozan round out the list), and would rank 33rd out of 56 players since 1977-78 -- good but not close to Harden.
Because Harden has been so efficient in such a large role, the Houston Rockets' offense sees similar benefit with him on the court. While Houston's offensive rating is a respectable 103.0 per 100 possessions when Harden sits (which would be good for 21st in the league), it surges to 115.3 with him -- better than any team has managed over the course of the full season. Overall, the Rockets have the league's third-best offense on a per-possession basis.
The verdict
Whose case is stronger? It's close enough that I could offer a diplomatic answer: Harden's efficiency is better for a team (like Houston) with more offensive weapons, while Westbrook's sheer ability to create offense by himself is better for a team (like Oklahoma City) with defensive-minded role players. But that's not a very compelling conclusion.
The one key factor we haven't yet discussed is turnovers. Both players are on pace to surpass Charles Barkley's NBA record of 4.7 per game according to Basketball-Reference.com. Given everything they do for their teams, those turnover rates are understandable, but that's more true in Westbrook's case. He's committing turnovers on 15.8 percent of the plays he uses (barely more than the average of 15.0 percent for point guards), as compared to 19.5 percent for Harden.
The difference in turnover rates helps mitigate Harden's efficiency advantage. In terms of a simple offensive rating of points scored per play used, Harden still has the edge (98.6 points per 100 plays to Westbrook's 91.4), but it's no longer as impressive as his true shooting advantage.
A good rule of thumb, derived by Houston Rockets VP of basketball operations Eli Witus, is that each extra percent of a team's plays an individual uses is worth about 1.25 points per 100 possessions in efficiency. In that case, Westbrook's usage advantage (8.5 percent) is worth more (about 10.7 points per 100 possessions) than Harden's superior efficiency (7.2). So by a narrow decision, I'd say Westbrook has been more valuable offensively this season.