Are the NBA's superstar foul-chasers suddenly in trouble?

When Carmelo Anthony was ejected from Sunday's Oklahoma City Thunder loss in Portland for elbowing Blazers center Jusuf Nurkic in the face while driving to the basket -- a play that was called a shooting foul on Nurkic before being overturned by replay review -- it caused the Thunder's frustration with referees to boil over.

Asked about Russell Westbrook's 2-for-7 shooting from the free throw line, Oklahoma City coach Billy Donovan instead took the opportunity to vent about his team's free throw differential.

"What's more concerning to me is our opponents have gotten to the free throw line 50 more times than we have," Donovan said. "And we've got a player in Russell who clearly, historically in this league, has gotten to the free throw line as much or if not more than anybody else in this league."

"We haven't been getting the benefit," Paul Georgesaid. "Every night, we haven't been getting the benefit of the doubt. I don't know what it is, especially for Russ. He attacks the basket, and so many of his plays at the rim are questionable, and he's not getting the benefit of the doubt."

Those complaints cost Donovan and George $15,000 each in fines announced by the NBA on Wednesday, along with one of that amount for Westbrook. But do the Thunder have a legitimate gripe?

Fewer free throws for best at drawing fouls

Last season, Westbrook averaged 10.4 free throw attempts per game, second in the league behind former teammate James Harden of the Houston Rockets (10.9). Both players have seen their attempts decline dramatically this season. Harden is down to 7.9 attempts per game, while Westbrook's 5.6 represent a drop of more than 40 percent.

Even when we account for Westbrook's decreased role in the Oklahoma City offense, the percentage of his plays (shot attempts, trips to the free throw line or turnovers) that have resulted in free throws is down substantially. That gives him something in common with most other players who averaged at least six free throw attempts per game in 2016-17.

Beyond Harden and Westbrook, seven other players have seen their percentage of plays ending at the free throw line decline by at least three percentage points in the early portion of 2017-18. While some of these can be explained by role changes (Jimmy Butler and Danilo Gallinari, for example, are spending more time in catch-and-shoot situations with new teams, as Kyle Lowry is despite staying put in Toronto), that's insufficient to explain all of the drop-offs.

Certainly, some regression to the mean should be expected for the leaders in any category, particularly over the small sample size of the season's first 10 games or so. But this decline is much larger than a similar group saw over the first 10 games of 2016-17. Then, the top 20 players in free throw attempts per game the previous season saw their free throw attempt rate fall by 0.6 percentage points -- less than a third as much as the 2.1 percentage-point decline so far for 2016-17 free throw attempt leaders.

With Harden and Westbrook joined by Giannis Antetokounmpo, Kevin Durant and LeBron James, it's a change that has affected some of the NBA's biggest names.

Westbrook's cause for free throw decline is unique

This season's emphasis on how to officiate continuation and contact on jump shots is an obvious explanation for the drop in stars' free throw rates. Before training camp, the NBA's "points of education" clarified that a jump shot should result in a shooting foul only if the player had begun the upward motion to shoot by the time the foul was called. (On a drive a player must only have gathered to shoot before illegal contact for a shooting foul.)

The change has been colloquially referred to as "the Harden rule," and indeed it appears to have cost him many of the free throws he got last season. Per Basketball-Reference.com, Harden has drawn six three-shot fouls in 11 games after benefiting from a league-high 122 of them in 2016-17. That difference alone would account for 2.8 free throw attempts per game, nearly all of Harden's decline. (Of course, some of the fouls Harden draws beyond the arc will still result in two free throws if the Rockets are in the bonus.)

However, the three-shot foul was never such a big part of Westbrook's arsenal. He had just 28 last season, according to Basketball-Reference.com, so this season's total of two doesn't represent a substantial change. That accounts for less than half a free throw per game, again assuming none of the non-shooting fouls result in free throws.

Instead, as George observed, Westbrook is drawing fewer fouls when he drives to the basket. According to data provided by Second Spectrum, 10.9 percent of Westbrook's drives last season resulted in shooting fouls. This year, that's down by nearly half to 8.0 percent of his drives.

That change can't necessarily be attributed to a different standard for continuation -- the leaguewide shooting foul rate on drives has increased from 10.2 percent to 11.1 percent, via Second Spectrum data. And the shooting foul rate on drives for the group of players who averaged at least six free throw attempts per game last season has actually increased by the same amount.

Intriguingly, something similar is true of George, whose rate of shooting fouls on drives has dropped from 12.3 percent to 6.1 percent according to data provided by Second Spectrum. (Anthony, by contrast, has seen his shooting foul rate on drives increase from 13.5 percent to 18.2 percent via Second Spectrum data. His decline in free throw rate can largely be attributed to having the ball in his hands less frequently.)

Ultimately, we're talking about a handful of calls over the season's first nine games, so odds are the explanation is mostly random chance. (Based on last year's rate of shooting fouls drawn, you'd expect Westbrook to have drawn 14 of them on drives so far this season. He's actually drawn 10.) But it's understandable those missing calls would be frustrating to an Oklahoma City team that is still working to build chemistry after adding Anthony and George.

All six of the Thunder's losses have come by single digits, three of them by four points or fewer. Westbrook getting back to the free throw line as often as he did last season might be enough to turn some of those close losses into Oklahoma City wins.