On Friday, Harrison Barnes provided a succinct explanation for the problem that type of differential poses: "Threes add up a lot faster than twos."
As expected, defending the 3-ball was the first topic broached at Roy Williams's weekly press conference in advance of Saturday's clash with Duke to determine the ACC's regular season champion.
"We do have to get out and guard the three better," Williams said. "We have to get closer to challenge them more. You're not going to stop Duke from shooting 3-point shots because that's what they practice every day. We've got to do a much better job getting closer to the shooter, trying to make sure that we get a hand up on the shot [and] not giving a pose after the ball has already been released."
The ninth-year UNC head coach recently broke down film of Duke's 36 3-point field goal attempts, grading and classifying the shots into nine different categories. While media talking points focus on dribble penetration and inability to fight over and around screens as the primary issues for the Tar Heels' perimeter defense, Williams informed reporters that there's much more involved.
"I went through 36 3-point shots and there is nothing that is a common thread more than five times," Williams said.
Here are some examples of how those 36 attempts broke down: dribble penetration and kick out (4), poor job going underneath a screen (5), well-defended make (1), stare-downs, such as Austin Rivers's game-winner over Tyler Zeller (4), step-backs (2), staggered screens at the elbow (2), double-screens at the top of the key (2-3), cut to lose defender (1), pass fake (1), diagonal pass from 5-man to 4-man (2).
That's only a fraction of the attempts, but the point is clear: Duke's offense emphasizes the 3-point shot, but does so in a variety of different ways. That's the difficulty in defending the Blue Devils.
"We just have to keep the ball in front of us," sophomore point guard Kendall Marshall said. "If we're not in a position where we're constantly helping, then we're not having to rotate as much and I think that will help our cause a lot more… We just have to be aware of where their shooters are and make it tough for them."
That task would be easier if there were only one or two options for Duke from long range, but that's not the case. Andre Dawkins, Seth Curry, Ryan Kelly and Rivers have all not only made at least 40 3-pointers this season, but they are all shooting above 39 percent from behind the arc.
Kelly presents defensive problems as a 6-foot-11 forward that can pull the ACC's top shot blocker in John Henson away from the basket.
"It does make it tougher," senior forward Tyler Zeller said. "They stretch a defense a lot, so it makes it so that John can't be at the rim as much to challenge shots. So it does change the dynamic of our defense."
But the glaring 3-point differential from this season's first game between these two programs is not one-sided. North Carolina only connected on 1-of-6 3-pointers, bringing its four-game total against Duke over the past two seasons to 9-of-37 (24.3 percent).
"We need to make more and they need to make less," Williams said.
The Tar Heels missed 12-of-14 3-pointers at Cameron last season, including all six of their second-half attempts in a game they lost despite holding a 16-point advantage in the first half.
North Carolina's offense is predicated on balance. On Feb. 21, N.C. State's game plan was to collapse the post and force UNC's guards to knock down shots from the perimeter. Zeller was held to 14 points on 3-of-7 shooting, but his teammates drained 10-of-19 3-pointers in coasting to the victory. That, however, hasn't been the typical response this season for a team ranked 12th in ACC play in 3-point field goal percentage (30.2).
After Zeller scored 19 in the first half against Duke earlier this month, the Blue Devils collapsed on the post. The Tar Heels made just one second-half 3-pointer, but Barnes utilized his size advantage to score 19 points over the final 20 minutes.
"I would love nothing more than to score five points and win the game just because all of our guards are shooting so well," Zeller said. "I'd love to catch the ball, throw it back out and have confidence that they'd knock it down."
All eyes will be on the 3-point line on Saturday night, and for good reason. In Duke's biggest wins of the season – Michigan State, Michigan, Kansas, North Carolina and Florida State – it averaged 11.8 made 3-pointers.
It's up to the Tar Heels to minimize that blitz from long range with solid defense and timely perimeter shooting.