After their two worst defensive performances of the season, giving up 1.23 and 1.21 points per possession to North Carolina State and Miami respectively, Duke head coach Mike Krzyzewski added a wrinkle he almost never relied upon in his entire coaching career when he had his team play zone exclusively against Louisville. With the Cardinals relying on dribble penetration and one of the worst three point shooting teams in the nation, Duke’s zone defense held them to its third lowest offensive output at 0.87 points per possession.
However, it seems that this was only a temporary fix. Duke was back to its traditional man-to-man defense in its next game against St. John’s, and many of the deficiencies highlighted below were on display.
Duke currently sits as the 49th ranked defense by Ken Pomeroy, allowing 0.943 points per possessions. There is no questioning Duke’s offensive talent (currently ranked 5th) but if it wants to become a true championship contender, they need to find their defensive identity.
The first issue with Duke’s defensive is their lack of transition awareness, which can lead to easy baskets for the opponent. According to hoop-math, Duke is one of the worst teams in transition allowing a 56.8% effective field goal percentage, 262nd in the nation. Their guards struggle in this department by not having proper floor spacing to prevent opportunities, failing to slow down the ball handler or not seeing runners on the wing. Watch how the guards can get caught ball-watching, letting players leak out behind them or run right by them leading to easy baskets.
The Blue Devils weren’t much better in halfcourt man to man situations, either. They have allowed 47% on two point field goals, including 56.7% at the rim. Guards Quinn Cook and Tyus Jones have struggled mightily against dribble penetration, which has allowed easy drives to the rim and forced the Duke defense to rotate heavily leaving open passing lanes available. While the guards can pressure the ball well when the opponent is not dribbling, once the ball is put on the floor they have a hard time containing penetration. Combine this with their small size (6’1″ for Jones, 6’2″ for Cook) allowing offensive players to shoot over them, and the Duke guards don’t provide much defensive resistance.
Elsewhere, junior wingman Rasheed Sulaimon has the potential to be an impact defender but he is having trouble finding expanded minutes in the guard rotation, playing just 49.1% of available minutes. He can be a fierce on-ball defender, though, harassing opposing guards into bad decisions. If he can find a way to steal more minutes – and he may need to, considering the defensive deficiencies here outlined – he could be a big help on the defensive end. He can defend dribble penetration and is relentless on defensive, forcing turnovers and taking the offensive out of rhythm.
Freshman forward Justice Winslow is also a player who was expected to make an impact defensively for the Blue Devils, and for the most part, he has. Unfortunately, he still struggles with off-ball rotations and movement, leading to easy baskets. At times, Winslow can really muck up an offense by shutting down the opponents’s best player, not even letting them get a touch. His length and agility allows him to cut off dribble penetration, forcing opponents into tough jump shots, like the one below.
While arguably their best defender, though, he is still prone to the freshman mistakes, which usually manifest in him not recognizing rotations or off-ball movement. This can lead to some easy baskets that should otherwise be preventable by a more experienced defender.
Duke doesn’t have the big men protecting the basket necessary to cover the mistakes of the guards. Amile Jefferson and Marshall Plumlee don’t strike fear in the hearts of drivers, and while Jahlil Okafor is not a terrible rim protector, he is averaging just 2.0 blocks per 40 minutes pace adjusted, one of the lowest among centers in DraftExpress’s top 100. Teams will still hesitate to challenge Okafor, but he can be scored upon at times. When he challenges shots, he is a capable shot blocker, but he isn’t always in position to challenge at the rim.
Okafor can also be taken away from the rim by putting him in ball screen action, as teams are starting to realize Okafor doesn’t have the best lateral quickness and he can be exploited on pick-and-rolls. Even when dropping back on ball screens, quick guards can get by to the rim, as Okafor hasn’t quite mastered ball screen defense yet.
Teams will start to put Okafor in more ball screen situations if Duke stays in a man defense and this is why Sulaimon is one of their more important defensive players as he has the ability to clean up mistakes on that side. Okafor is beat out of the ball screen again and after the help cuts off penetration, Sulaimon hustles to force a contested, off dribble three pointer. This effort level will be necessary as the season continues and his minutes will be something to monitor, along with the performance of Duke’s overall defense.
Duke is also just an average defensive rebounding team, allowing all opponents to secure 28.3% of offensive rebound changes (62nd in the nation) and ACC opponents 31.7% (7th in the conference). This compounds their issues, as they struggle to end possessions as well.
While Duke has the athletes to be a strong defensive team, their struggles so far have lead to a middling defense for a team with championship aspirations. It is a team with a distinct defensive identity that they have had for years, but without the caliber of defensive personnel this campaign. While the zone defense worked for a few games, Coach K seems hesitant to rely on it long term. It may be a way to hide the small guards and force teams to make long distance shots over them while allowing Okafor to patrol the paint, where he affects the game when engaged. Coach K will need to find fixes quickly for the man to man struggles or revert back to the zone defense that worked for a few games if he wants the team to become the national champion.