Duke’s defense is bad again. Can they fix it in time to be national champs?

Duke has made a habit out of playing with fire early in the season. On Saturday, the (now former) No. 1 team in the country finally got burned.

Boston College scored on Duke at will on its way to an 89-84 home win. This is troubling in itself: BC had lost 25 straight games against ranked teams and finished in the cellar of the ACC the last two years. But what was really jarring was how easy the Eagles made it look on their way to putting up 1.2 points per possession in the win.

Boston College rained three-pointers all afternoon (15-of-26 from deep) and cut up the Duke big men on switches to score in the paint. BC’s three guard attack of Ky Bowman, Jordan Chatman, and Jerome Robinson all finished with at least 22 points.

This was Duke’s first loss of the year, but the pattern of the game still felt familiar. Duke has already needed an 18-point comeback to beat Texas and a 17-point comeback to defeat Florida this year. This team has an underlying problem: their defense just isn’t good right now.

Duke has the No. 1 in offense in the country, but it’s now down to No. 71 in defensive efficiency. If you think that ocean-wide split is unique, just know that Mike Krzyzewski is used to it at this point in the season.

If it seems like there is a story on Duke’s struggling early season defense every year, it’s because there is. Sometimes Duke figures it out and they win the national championship. Sometimes they don’t and they lose in the first round of the NCAA Tournament to Mercer.

Krzyzewski would probably like to remind you the 2015 team struggled early on defense, too. Duke entered the NCAA Tournament at No. 57 in defensive efficiency that year. By the time the tournament was over, Duke was cutting down the nets and their defense was all the way up to No. 11 in the country.

Maybe Duke will solve their problems by the end of the year like that team did. Or maybe they won’t and they’ll suffer a similar fate to their teams that have been knocked out early.

The 2014 team with Jabari Parker never figured it out, finishing the year at No. 86 in defensive efficiency and infamously losing to Mercer. The 2016 team with Brandon Ingram also finished No. 86 in defensive efficiency and bit it against Oregon in the Sweet 16. Last season’s purported super team lost in the round of 32 to South Carolina with the No. 47 defense in America.

Let’s bring it back to the 2015 team for a moment, if only because there are some obvious parallels between this year’s team and that one. Most notably: both teams were heavily reliant on freshmen. It was Jahlil Okafor, Tyus Jones, Justise Winslow, and Grayson Allen back then. Now it’s Marvin Bagley, Gary Trent Jr., Trevon Duval, and Wendell Carter.

In 2015, Okafor was a monster inside scorer but struggled to defend the rim. You can say the same thing about Bagley right now. Carter wasn’t much better. When the BC guards got Duke on a switch, they were able to burn their big men to the cup:

Even for the most talented freshmen in the country, there’s still typically a huge learning curve on the defensive side of the ball. There’s so much nuance to positioning and switching that just isn’t taught at the high school level.

The good news for Duke is they have plenty of time to figure it out. The bad is news is that they don’t have a player like Winslow — an elite defender whose move up the lineup to the four ultimately ushered in Duke’s stellar defense in 2015.

Teams with Duke’s combination of length and athleticism are supposed to be able to play lockdown man defense. Instead, Duke has been more and more willing to go zone early in the season.

For Krzyzewski, zone is a life jacket. It’s not going to teach Duke to swim on defense, but it might keep them afloat long enough for their offense to save them. Remember, they are No. 1 on that side of the ball for a reason.

This is not a typical Krzyzewski team. In recent years, Krzyzewski has relied heavily on spread lineups with a natural wing playing the four. This year he’s starting two traditional big men up front in Bagley and Carter. Theoretically, that should give Duke more size and strength up front to help lock down the paint. The problem is those players still look lost defensively.

Will that change? It certainly could. It’s only December and the games won’t really count for Duke until March. When you’re starting four freshmen, it’s going to take some time. But at the moment, Duke doesn’t force any turnovers (No. 324 in the country, per KenPom), they allow too many offensive rebounds and don’t have the speed they’re accustomed to on the defensive end.

Duke still has the highest ceiling of any team in the country strictly based on their talent level. What they need now is cohesion. That means finding a willingness to share the ball for a team that has a player with legitimate NBA aspirations at every spot on the floor. That also means finding a way to defend on a string and finish possessions.

So far, it’s a work in progress. For Duke, it always is.