As Tuesday night’s game against Michigan State unfolded, and Grayson Allen did his best impression of JJ Redick vs. Texas on the offensive end, Duke did something I can’t ever remember seeing a Coach K team do. For 40 minutes, the Blue Devils abandoned their trademark man-to-man and defended exclusively with a 2-3 zone.
A lot of time when teams play zone, the narrative is that they “sat back”. This implies that the team packed the area around the lane and refused to challenge the ball on the perimeter. I don’t think that’s an accurate description of how Duke defended. The Blue Devils routinely closed out to put pressure on the ball handler with one or both feet above the three-point line. They were also active in the passing lanes, leading to 8 steals from guys in the top two positions.
Early on, however, Duke struggled to defend the interior because of their commitment to defending around the three-point line. Michigan State had several baskets early in the first half that followed a similar pattern: Pass to the wing–>flash from the opposite block to the strong side elbow–>pass from the elbow to the short corner/block. Michigan State scored no fewer than 8 points with this formula in the first half. It wasn’t until Duke adjusted their positioning that the Spartans had to find other avenues to score.
So how did Michigan State get the ball to those spots so easily? To put it simply, Duke sent two guys to the ball. In the photo below, you can see Miles Bridges has caught a pass on the wing and Wendell Carter has closed out to guard the ball. Grayson Allen was just guarding the ball at the point, and is rotating over towards Bridges on the wing. Up to this point, things are okay. There’s no one in the high post, and Marques Bolden is matched up with a big on the strong side block.
What happens next is more problematic. Michigan State flashes a cutter in behind Allen to the high post, forcing Bolden to temporarily guard two players. Ideally, Allen would make a choice at this point – either take the ball, or take the cutter. Early on in the game the Blue Devils frequently chose option C: guard nobody. You can see in this second photo that Allen is about halfway between the ball and the high post, but his body position makes it impossible for him to truly be guarding the cutter. Carter has stayed in an extended position because Allen is not close enough to challenge Bridges on a shot. The result is that Bolden is responsible for both the player on the elbow and the man creeping along the baseline just out of the picture.
On the play in these photos Bridges actually took (and made) a jump shot, but these positioning issues were problematic throughout the first half. The pass would go over Allen (or another guard) into the high post, the middle defender would step up, and the dump down to the baseline would be wide open because the wings were not dropping fast enough back to the block.
Duke did a much better job in the second half of taking this option away by doing two things. First, the guards fully committed to the ball on the wing. They bumped the baseline defender back to that short corner consistently and quickly. Part of that could also be attributed to Javin DeLaurier, as he can cover that rotation faster than Carter. Secondly, the middle defender refused to over-commit to those high post cutters in the second half. Michigan State showed very little interest in shooting off of those initial entry passes. When Duke stopped stepping up so high from the baseline, they were able to further clog that high-low passing lane.
There are probably a number of reasons for Coach K deciding to start with the zone against Michigan State, but the ability of the team to adapt to Michigan State’s preferred method of attacking it allowed him to stay in the defense for the whole game. That will be a useful weapon going forward. For all the depth Duke has inside, the perimeter may still be a little thin in terms of guys who will truly be trusted to play significant minutes in February and March. Having this defense as an option against teams who would like to attack the basket and create foul problems will be a terrific asset down the road.