You could argue that Luka Dončić is an improved defender this season — but you could also argue the opposite. The important part is what he’s doing right.
Lots of advanced defensive stats support that Dončić has improved as a defensive player this season, many of them laid out by Yahoo’s Kelly Iko in his recent piece about Dončić’s defensive improvement after the Los Angeles Lakers stymied the Houston Rockets and made Kevin Durant look uncomfortable offensively (which is like making a chocolate chip cookie look unappetizing, it just doesn’t happen) for the Lakers’ sixth straight win.
Some of the stats highlighted in that piece: Dončić is 95th Percentile in contest rate and statistically one of the best isolation defenders in the NBA at .844 points allowed per possession. He also has a much-improved STOP% at 2.9, meaning his status as “huntable” on defense may not hold up anymore.
Dončićs defensive impact isn't statistically clear
However, you could just as easily demonstrate that Dončić has been a slightly worse defender all season, from stats on the same pages linked above; he was 91st percentile in contests last year, so this is only a marginal shift, and players are actually shooting a higher percentage on shots Dončić contests this season, meaning each contest has been less effective. He actually has a worse defensive rating this season than he did last year. Although, this stat captures a ton of team context so his rating may be better last year because he spend a good portion of the season with the Mavs, a better defensive team than the Lakers.
Iko pointed out in his piece that Dončić’s recommitment to fitness, saying how he lost 20 pounds this offseason and “is now quick enough to move his feet with ball-handlers in space and has an improved burst, which helps with his reaction time.” Perhaps that is the case, but it is hard to know from traditional or advanced metrics if Dončić’s offseason conditioning has any relationship with such an unclear statistical picture.
What is certainly better is his stats lately, having improved his defensive rating markedly during the Lakers’ winning streak from 115.3 (which isn’t very good) to 105.1 (which is quite good). Again, that's as much reflecting team performance as his own impact but it's impressive considering the quality of opponent, beating the New York Knicks, Minnesota Timberwolves, Houston Rockets and Denver Nuggets in that stretch, which was a precondition to getting out of the doldrums of the middle of the Western Conference.
Effort is the key to Dončić's defensive improvement
The Lakers were in the Western Conference gladiator pits with all their good friends: the Minnesota Timberwolves, the Denver Nuggets and the Houston Rockets. All squarely behind the San Antonio Spurs but not sufficiently ahead of the Phoenix Suns, the four horsemen of mediocrity fought tooth and nail for the three-four-five-six positions in the West.
Perhaps therein lies the explanation for Dončić’s defensive improvement: a realization that the Lakers needed to focus and start winning basketball games lest they risk falling into the Play In. Effort is not quantifiable, per se, but it may be explainable. How pivotal each of these games was for the Lakers may have uncorked Dončić defensively — and there is no reason that it shouldn’t have.
Defense in the NBA comes down to a number of physical and mental factors, but being an average-to-above-average defender boils down to two things: effort and size. There was never a reason that Dončić could not have been a league-average defender with his massive frame, and his basketball instincts and physical traits are positively earth-shattering; he could be a great defender if basketball was played on a spreadsheet.
Can Dončić sustain his defensive output?
This is good news for Lakers fans, as Dončić seemed to understand that the more important the game, the more he must commit and recommit to defensive possessions. However, we have the same Luka Dončić conversations every single year: can he sustain this level of effort?
It is super taxing to be third in the NBA in usage rate; Dončić is the center of gravity for the Lakers’ entire basketball universe, and he has repeatedly struggled in his career to sustain defensive effort throughout four playoff rounds.
I do not think there is any statistically significant improvement in Dončićs defensive impact this season, but I do accept there is one in a very small sample size of the Lakers’ recent winning streak. The question, now, is which guy will show up in the playoffs? The much larger sample size-supported meh defender, or the locked-in, committed physical defender?
You may accuse me of being purely pessimistic, but I am not: there is no good reason why Dončić cannot be this good all the time. And he clearly wants to be, so let’s see it. I, and millions of other NBA fans, want nothing more than max-output Luka all the time.