I realize this "Duke is really bad at defense" thing can seem like a rite of winter, but there's simply no other way of putting it:
Duke is really bad at defense.
If you don't believe me, take Coach K's word for it. "We're not a good defensive team," Mike Krzyzewski said after his team allowed Boston College to score 1.20 points per possession in the Blue Devils' 89-84 loss at Chestnut Hill.
Yes, it was just one game, and yes, it's still early in the season. Nevertheless, Duke has dug itself a deeper than expected hole on defense early in the season. My guiding assumptions with respect to this team going forward can therefore be summarized follows:
-- When a defense shows you who it is, believe them.
-- Now let's talk about that offense. ...
Here's what we think we've already learned about Duke on both sides of the ball after just 12 games:
A collapse on the perimeter
In fairness to the "it was just one road game -- no need to panic" school of thought, BC made 15 shots from beyond the arc against Duke. Last season, such a performance would have ranked among the top 1.3 percent of perimeter outbursts in all Division I games.
So, no, Trevon Duval, Gary Trent Jr., Grayson Allen & Co. will not be regularly allowing opponents to make 15 3-pointers the way the Eagles did. That said, Duke's recurring problem is that it is allowing an unusually high number of 3-point attempts.
The one constant of an otherwise variable Blue Devil defense for, literally, the balance of this century has been that Coach K's teams chase opposing shooters off the 3-point line. In fact, past Duke teams -- including the young ones -- have limited opponents' 3-point attempts even in November and December.
That isn't happening this season. Duke's five quality opponents (Michigan State, Texas, Florida, Indiana and Boston College) have devoted 36 percent of their shot attempts to tries from beyond the arc. Even making due allowance for today's brave new world in which everyone's shooting more 3s, that's a moderately high number relative to the rest of Division I.
Prior to 2017-18, Duke had allowed an opponent to make more than 11 3s in a game just once in the past 16 seasons and 572 games. This season, however, Portland State (12 made 3s), Elon (14) and, of course, Boston College (15) have all eclipsed that number.
Nor is the perimeter the only source of defensive worry for Coach K.
A question mark in the paint
The example of Duke's 2014-15 national championship team makes me hesitant to write off a Blue Devil defense early in the season. After all, that Duke team rather (in)famously allowed NC State and Miami to score a combined 177 points in back-to-back losses. Yet Jahlil Okafor, Justise Winslow, Amile Jefferson, Quinn Cook, Matt Jones and, yes, Allen still cut down the nets in Indianapolis that April.
It turns out, however, that in each of the past three seasons -- including 2014-15 -- Duke's early-season rim defense against quality nonconference opponents has been a good predictor of what the Blue Devils will subsequently display in that category in ACC play. So far this season, Duke's performance in that area has been mediocre at best.
The Blue Devils' five top-flight opponents so far have converted 54 percent of their 2-point tries. Across a like number of games in early 2014-15, by contrast, that number was 47 percent, and just like the current team, Okafor & Co. recorded those stats in four neutral-site games and one true road contest.
In conclusion, it's likely that Duke's defense will be a source of worry and discussion for the entirety of this season. But it's also likely, in my estimation, that said season could extend all the way to April.
Now the good news for Duke fans
Even when losing at BC, Duke characteristically scored more than a point per possession. The Blue Devils' offense has been excellent this season, and what's notable there is that Coach K's guys have been able to score points while being unable to make 3s against quality opponents.
In five games against major conference teams, Duke has connected on just 29.7 percent of its 3s. However, that poor shooting from the perimeter hasn't prevented the Blue Devils from racking up a sizzling 1.17 points per trip against those same five opponents (so watch out if Trent really is finding the range from out there, as would seem to be indicated by his past two outings.)
I realize I'm taking my life in my hands with this phrasing, but this season Duke is scoring points the North Carolina way. Thanks to a pretty low turnover rate and an insanely high offensive rebound percentage, the Blue Devils' shot volume has been little short of incredible.
If the scenario I've outlined with respect to Duke's rim defense does play out that way going forward, you might hear critiques of what guys such as Marvin Bagley III and Wendell Carter Jr. are doing or not doing on that side of the ball. That's fair enough, of course, but keep in mind that what these two freshmen are doing on the offensive glass is giving the Blue Devils a shot at having their best offense in years. And that's saying something.
This defense might not go into the books as one of Coach K's best ever, but this offense very well could. It promises to be a highly entertaining combination to watch.