Through the first week of the NBA season, the Chicago Bulls are tied with defending champion Oklahoma City Thunder for the league lead in defensive rating. Chicago’s 104.4 mark is more than 12 points better than last season.

The Bulls rank seventh in the NBA in opponents’ field-goal percentage (44.7) and first in opponents’ three-point accuracy (26.3). Some of that success can certainly be attributed to luck, given that Chicago’s first three opponents last season ranked 17th, 18th, and 30th in three-point shooting.

Still, the Bulls are forcing opponents into a negative efficiency differential and are surprisingly stingy from nearly every zone, mid-range aside. They rank sixth in opponents’ efficiency within five feet, seventh from five to nine feet, 13th from 10 to 14 feet, 29th from 15 to 19 feet, second from 20 to 24 feet, and first from 25 feet and beyond.

Interior woes plague Chicago’s top-notch defense

Yet the Bulls are still getting crushed in the paint—and I mean absolutely decimated. After allowing a league-leading 54.0 points in the paint last season, Chicago once again tops the leaderboard, surrendering a staggering 64.7 points per game through three contests. To be fair, their first three opponents were strong inside last season, ranking third, fifth, and 24th, respectively.

Nevertheless, it’s a concerning trend. Bulls opponents are getting an abundance of paint touches, averaging 42.7 field goals from within five feet of the rim, the highest mark in the league by a wide margin, seven more than second-place Washington Wizards. Chicago has been stingy at the rim, but without a true rim protector. Which poses the question: How long can that last? The Bulls rank 15th in blocks per game, but it’s been a team effort, with no player averaging more than 1.0 swats.

The Bulls’ defensive intensity is noticeably higher this season. Matas Buzelis is a strong weak-side defender, Patrick Williams is playing with more energy, and Tre Jones and Isaac Okoro form a formidable perimeter duo. Yet, like last season, Chicago lacks an interior presence that intimidates opponents—and with the team ranking 29th in turnovers forced, there’s little margin for error.

Chicago deserves credit for stifling its first three opponents and surprising the league with a stellar defensive rating. Still, there’s reason for concern: opponents are scoring freely at the rim without a true difference-making presence.

On the plus side, four of last season’s top five defensive teams held opponents to a bottom-10 three-point percentage. That suggests the “opponents will start making threes eventually” crowd might be overestimating the Bulls’ impact on limiting quality three-point looks. Thus, giving up plenty of paint points while limiting threes isn’t necessarily a bad strategy.

Still, allowing easy opportunities isn’t consistent with quality defense. Sans Chicago, the bottom nine teams in points allowed in the paint are a combined 10-23. Yikes.

Chicago’s Achilles’ heel has long been its interior defense. Once opponents convert at a high rate from within five feet, trouble follows. So far, the Bulls haven’t faced an efficient paint squad—and won’t until they clash with the Milwaukee Bucks (second in field-goal percentage within five feet) on November 7. Until then, tightening their interior defense is imperative. Limiting three-point attempts has fueled Chicago’s early success, but a more balanced defensive approach will be key to sustaining it.