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The Close Out: A closer look at Isaiah Stewart’s defense

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The results have been mixed, but there’s reason for optimism.

NBA: Milwaukee Bucks at Detroit Pistons Rick Osentoski-USA TODAY Sports

Isaiah Stewart has quickly endeared himself to Detroit Pistons fans through hard work, hustle, and overall positive energy on the court. His coaches have noticed as well and have rewarded him with an increasingly larger role in the rotation. But Stewart’s ultimate career arc is going to depend a lot on how he develops defensively.

The rookie from University of Washington certainly has the strength and length to be a formidable presence in the middle. What was not so clear with Stewart as a draft prospect is how he would be able to defend when opponents pulled him out of the paint.

So far this season, the Detroit Pistons have been at their best with Isaiah Stewart. The team has a +6.3 net rating when he’s on the floor, the best of any player in the regular rotation. But the defense has been far more generous with Stewart playing as opposed to Jahlil Okafor and Mason Plumlee.

There’s several reasons for that even before getting to the small sample size. The youth-heavy bench and plenty of not-so-good defenders being the most notable. Opponents are shooting 42.7% from three on low volume when Stewart is in, the former of which is probably a lot of negative variance.

There are, however, real reasons beyond variance that Stewart lineups haven’t been good defensively. His lineups rank second-to-last among all Pistons in both opponents’ offensive rebounding and free-throw rate. And Stewart is one of the culprits.

The rookie center has shown a tendency to leave his feet prematurely on defense. Often it comes in the form of attempting to block shots he has no chance to alter. That leaves Detroit’s defenders out of position, forcing them to foul more and grab fewer rebounds.

Other times, Stewart’s energy and desire to make plays simply gets the best of him.

Against the Utah Jazz, he left his feet on a pump fake allowing Jordan Clarkson to get a pretty clean, in-rhythm look despite a solid recovery:

That is a good, not great shot, but the bigger issue is leaving his feet in a pick-and-roll situation. If Clarkson had opted to drive, the Pistons would have been left with two defenders trailing, and Utah would have been able to choose exactly who they wanted shooting a wide-open three.

Left on an island against Jrue Holiday, Stewart defended the initial drive pretty well but then left his feet on a fake against a smaller opponent, leading to an easy two points:

We’ve seen a fair amount of Stewart having to defend in isolation situations following screens and/or switches. Those events actually account for 17.2% of his defensive possessions according to Synergy data. Opponents are scoring at will in those instances—Stewart ranks in only the 10th percentile defending in isolation. But he has still shown some flashes of ability on which to build.

In the third quarter against Giannis, Stewart stays with him through the rim and makes these two points a lot more difficult than Giannis is accustomed to:

Matched against Stephen Curry earlier in the season, he stays with another former MVP into the paint and this time forces Curry to step out of bounds:

When Donovan Mitchell took his turn, he too was forced into a turnover when he was unable to beat the rookie big off the dribble:

Now those are obviously the highlights. The isolation defense numbers are probably among the most accurate defensive play-type numbers because it’s easy to identify the responsible defender. Stewart hasn’t been good in those situations, but he’s far from hopeless. It will take plenty of work, but Stewart is not so limited that he can’t make the necessary improvements and he’s a notoriously hard worker.

Because of the success attacking Stewart in isolation, opponents have also forced him to defend in space in the pick-and-roll. There’s no publicly available data because of sample size issues, but Stewart has seen mixed results in these situations as well.

He has a tendency to not show high enough and be stuck in the middle during his backpedal like here against the Miami Heat:

But when he does get the mechanics correct, he looks fluid enough to be a viable roll man defender.

Later in the Heat game, Stewart did a nice job cutting off Kendrick Nunn’s drive to force him left which ultimately ends in a turnover:

After he was pushed into a drop by Daniel Theis, Stewart slowed Jeff Teague enough to hand him back to Delon Wright and fall back to defend Theis near the rim. The other half of the defense broke down, but Stewart’s defense was picture perfect:

As the last line of defense against a Milwaukee staggered screen, he correctly read the coverage, dropped down to defend Brook Lopez and contested a drive well enough to force a short miss:

Stewart’s rim protection has generally been OK. Numbers at the rim against him are similar to Plumlee’s and better than Okafor’s. But the process is far more important than the results at this stage.

Some of the process needs to improve. Developing a feel for timing and positioning will come with experience. And those are the primary causes of Stewart’s defensive issues to date. Rookies doing rookie things are expected and shouldn’t affect long-term projections.

What Stewart is doing is showing that he moves fluidly enough to defend in space and accelerate in short areas to help recover. Whether he develops the finer, more nuanced aspects of defense is still an open question. But the baseline skillset appears to be there.