Deandre Ayton is 21 games into what is sure to become a long and productive NBA career, and the no. 1 pick in this summer’s draft has been every bit as advertised. He shows soft hands and preternaturally polished touch in the paint; he hoovers up rebounds at the best rate for any rookie in his class; he already looks like a potent partner for Devin Booker as Phoenix tries to build a superteam.

He’s not a perfect offensive player, but he’s excelled thus far—and done it all with a carousel at point guard. Ayton is averaging 16.4 points and 10.4 rebounds per game, which itself is a massively encouraging sign: Of the 33 retired players who averaged 15 and 10 in their rookie seasons, more are enshrined in the Hall of Fame than not, and the only players to do so since 2005 are Karl-Anthony Towns and Blake Griffin, who both developed into max-contract bigs.

But basketball is a two-way game, and Ayton has also been as advertised on the defensive end. His defensive numbers in college raised red flags about his potential on that side of the ball in the NBA, and rather than allay those concerns, he has only exacerbated them through his first quarter-season. Ayton’s defensive issues at Arizona were a bit of a puzzle, given his seemingly ideal physique for the job, but they glared both on the court and on the stat sheet. Essentially, the freshman’s block and steal numbers in college—which typically have a strong relationship with a player’s block and steal numbers in the NBA—were far lower than previous big men taken first overall, and none of his statistical comps in the broader lottery range turned into franchise cornerstones in the pros.

The same weaknesses have appeared in his nascent NBA career—again, easily visible both on the court and on the stat sheet. That’s not to say he can’t recover, but we can check off some potential reasons for the issues. It is apparent, for instance, that Ayton’s defensive lag was not the result of a poor system or a lack of effort that would be soon solved at the next level. Instead, he might just have real, persistent problems that make him easy to exploit. He’s already produced his share of lowlights, like the time he was a nutmeg victim four times in one game against the Raptors, or the time a Darren Collison crossover dropped him to the floor.

But Ayton doesn’t just lapse in the odd play that makes the rounds on Twitter; he struggles game after game, possession after possession, to anticipate and navigate the most basic NBA sets. Pick-and-roll defense is tricky, especially for a rookie big—and extra especially for a rookie big in 2018, when offenses can spread the floor around a point guard who can sink 25-foot 3s like layups. Even Anthony Davis saw his team’s defensive rating improve when he left the floor in his first two seasons. But some of Ayton’s fellow rookies aren’t having as much trouble.

To compare Ayton with Wendell Carter Jr., the no. 7 overall pick, in their November 21 meeting in Chicago is to illuminate the distinction between reactive and proactive defense. The box score shows Ayton (18 points, 12 rebounds, five assists) with the advantage over Carter, who grappled with foul trouble en route to a 14-point, five-rebound night in a 124-116 Bulls win. But their defensive discrepancy produced a greater impact on the game.

In the first six minutes of the first quarter alone, Carter forced three turnovers with shrewd pick-and-roll defense. Here, he met Isaiah Canaan with fluid lateral movement at the point of attack, forcing the (since-waived) Suns point guard toward the baseline instead of the basket until he stepped out of bounds and cost the Suns possession.

Five minutes later, he interrupted an intricate Ayton-Booker dance as the latter curled back in the direction of the pick. Carter maintained his balance with a swift flip of his feet and prevented Booker from both turning the corner toward the hoop and pulling up for a rhythm jumper. And once Bulls guard Ryan Arcidiacono had recovered to Booker’s hip, Carter retreated in the same moment to stymie a potential lob to the rolling Ayton. The defensive exchange was seamless, and the Suns’ play stalled—Booker picked up his dribble and jab-stepped to nowhere as Ayton was whistled for a three-second violation.

Ayton didn’t fare so well when defending pick-and-rolls on the other end of the court. Three times in that game, Zach LaVine charged at Ayton off a screen and scored a minimally contested layup. Not only did Ayton let LaVine dictate the direction he drives, but he didn’t even try to alter any of his shots once there. Even if he was consciously trying to avoid collecting a third foul in the second quarter, there are better ways to deter a shot at the rim. He wasn’t in foul trouble in the fourth, when LaVine coasted for the final layup in this triptych.

A stout defender is both balanced and direct when guarding the ball; Ayton is neither. Instead, he stands up straight and stiff and appears to react a beat too late, time and again, which makes it a challenge to mirror the ball handler’s movements—and also invites nutmegs and ankle-breaking legerdemain.

At least on an obvious pick-and-roll like those in the above clip, he knows what’s coming. At other points, Ayton suffers from recognition problems. Late in that Bulls game, Ayton simply lost Carter on a throw-in, letting his Chicago counterpart secure the game-clinching layup.

And at the basket, where one suspects Ayton’s size—7-foot-1 with a 7-foot-5 wingspan—would confer the greatest advantage, he has struggled the most. Against Chicago, Robin Lopez torched Ayton with a twirling post move that fooled Ayton into jumping twice at pump fakes.

A quarter later, when Lopez posted up again, Ayton adjusted by not bothering to jump at all, which yielded the same result: two points for Chicago and another made shot against Ayton in the paint. These examples come from one night to show a concentration of all his mistakes in a close game Phoenix lost in the final minutes, but they could have been selected almost at random from his defensive work thus far. And while some of these clips show solid moves from the likes of Darren Collison, he’s also Darren Collison—this isn’t quite Steph Curry dusting a center with his bag of tricks.

Ayton’s various failings coalesce into one broader illustrative statistic: When he defends an attempt within 6 feet of the hoop, opponents are shooting 65.5 percent, the highest for any player who’s faced at least 100 such shots. (Second and third from the bottom, respectively, are Nemanja Bjelica and Enes Kanter, who don’t quite serve as role models for aspiring rim protectors.) Carter and Jaren Jackson Jr. rank fourth and seventh, respectively, with allowed field goal percentages hovering around 50 percent.

Like most defensive numbers, this one depends on more factors than Ayton’s individual performance. His teammates play a role, and the 4-17 Suns allow the league’s second-highest shooting percentage as a team within 6 feet, as well as the most points in the paint. But it is a concern for their starting center specifically that he hasn’t influenced more shots.

A player’s success rate when defending an attempt within 6 feet is fairly stable year to year, as stingy at-rim defenders generally remain stingy at-rim defenders, and the most generous at-rim defenders generally remain generous at-rim defenders. And second, even a quarter-season of games is a useful sample to forecast rookies’ paths. This data extends back to the 2013-14 season at NBA.com/Stats, and in that span, rookies as effective as Carter and Jackson within 6 feet this early in the season include Joel Embiid, Steven Adams, and Kristaps Porzingis. (Jahlil Okafor is also among that group; it’s not a perfectly predictive measure.) Conversely, Ayton has by far the highest allowed field goal percentage among high-volume bigs in the sample; his only company in the upper 60s is wings like Kyle Kuzma and Jabari Parker.

One of the reasons opposing players finish so easily over and around Ayton is that he doesn’t block many shots. It’s not a surprise, given the LaVine clips above, that he’s blocked just 2.2 percent of opposing 2-point shots. That ranks 36th out of 43 qualifying centers this season and, more broadly, just 87th out of 119 qualifying rookie centers since 1974-75, when the statistic was first recorded. Carter (at 5.3 percent) ranks 21st out of the 119, and fellow rookie Mo Bamba (6.6 percent) ranks eighth. Jackson doesn’t qualify as a center in Basketball-Reference, but he would place in the top five with a 7.9 percent block rate. And pay attention to the Knicks’ Mitchell Robinson, whose 9.6 percent rate would rank second all time, behind only 7-foot-7 Manute Bol’s, if he maintained it for the full season.

Help isn’t coming for Ayton, either, because of both Phoenix’s roster and the dictates of strategy. While a few teams have found success playing two bigs together, the Suns can’t add another rim protector without sacrificing more shooting—Ayton hasn’t shared the floor with another traditional big for a single minute this year. They have gone the opposite way recently, demoting the nominal point guards they had been starting next to Booker and promoting rookie wing Mikal Bridges to add more shooting and let their max-extension guard run the offense. Canaan, who started 15 games before his release, wasn’t helping much in that area (34.7 percent from 3), and neither is Ayton.

After attempting one 3 per game in college, Ayton has taken just two total in his NBA career. His 78.6 free throw percentage suggests he has the shooting stroke to extend beyond the arc, but he hasn’t even experimented with the prospect. This is another area where a fellow rookie big man is lapping the no. 1 pick; the Grizzlies’ Jackson, the no. 4 overall pick, seems the inverse of Ayton. The 3-and-D 19-year-old is sinking 34.9 percent of his 2.2 3-point attempts per game, in addition to 73.3 percent of his free throws.

Jackson’s defense has been even more impressive for a plucky Memphis squad. He is one of seven rookies on record—and the first since Andrei Kirilenko in 2001-02—to combine 40-plus blocks with 20-plus steals in his first 20 career games. He’s a strong defender at the rim, and he is just as proficient remaining keyed on the ball as he is rotating to help from the weak side.

Unlike Ayton and Carter, Jackson has played the majority of his minutes as a 4 rather than a 5, but that’s a workable arrangement because both he and center Marc Gasol can stretch the floor. The pair shines on defense, too—in 287 minutes with Jackson and Gasol playing together, the Grizzlies boast a 94.1 defensive rating, which is second best of any NBA pairing that has played as many minutes. When that duo isn’t on the floor, Memphis’s defensive rating climbs north of 109.

Unlike Ayton, Jackson entered the NBA with sturdy defensive credentials that would seem to portend future greatness. His college block rate was the highest on record for a lottery pick, wrestling the top spot away from Anthony Davis. Though he stills needs to rein in the occasional bout of handsiness—his four fouls per game lead the league—he possesses all the physical tools and instinctual knowledge necessary to command a top defense for years to come.

Jackson projects as a more complete player than Ayton, anyway, and standout bigs like Carter and Robinson might, too, even if their cases are fuzzier due to Ayton’s offensive advantage. The Suns center went no. 1 overall in a loaded draft and is prepared to average a double-double for his whole career, but defense is half the game, and shooting is growing into something like half the game, too. Ayton would have dominated the ’90s, but his peers might be better choices to lead a title contender in this decade and the next.