UNC’s generous 3-point defense is a cost of its championship style

One of UNC’s main downfalls last season was weak three-point defense. Overall, Carolina allowed opponents to make 357 of 940 attempts from deep for a 38.0% mark, all of which were the worst figures of any ACC team in at least the last nine years (122 individual team seasons). Given the game’s sharp turn towards heavy three-point shooting over the last decade, we can safely assume the 17-18 Heels’ gross numbers were the worst in ACC history.

This is part of a larger pattern that does not appear to be trending the right way. Only one ACC team besides Carolina has ever allowed 300 three-point makes in a season - Boston College last year - and the Heels have done so in each of the last three campaigns (308/850 (36.2%) in 2015-16 and 319/939 (34.0%) in 2016-17). In other words, a team that made back-to-back national title games and won the second one allowed its opponents to chuck up nearly 1,800 long balls and convert a tidy 35% over 80 games in that span.

Indeed, the Heels haven’t been a very stiff three-point defense for some time now. The stat is understood in the analytics world as one of the more “fluky” sports data points — Ken Pomeroy famously declared that defending a three-point shot doesn’t matter so much as limiting attempts, and with a shot that goes in, on average, about 35% of the time, there’s a ton of variability just by the low hit percentage of the endeavor. That being said, almost a decade of data should provide some useful information, right? Over the last nine seasons with available data (since 2009-10), the cumulative rankings of ACC teams’ three-point percentage defense is as follows (guess who’s first!):

1. Duke: 31.1% (1676/5392)

2. Louisville: 31.8% (834/2624) (four seasons)

3. Virginia: 32.4% (1777/5479)

4. Syracuse: 32.5% (1279/3937) (five seasons)

5. Maryland: 32.6% (1051/3219) (five seasons)

6. Virginia Tech: 33.0% (2081/6311)

7. North Carolina State: 33.2% (1920/5780)

8. Clemson: 33.5% (1775/5300)

9. Miami: 33.5% (1976/5900)

10. Georgia Tech: 33.7% (1891/5615)

11. Florida State: 33.7% (2112/6271)

12. North Carolina: 33.9% (2516/7430)

13. Pittsburgh: 34.4% (1117/3248) (five seasons)

14. Wake Forest: 34.7% (1964/5667)

15. Notre Dame: 35.3% (1262/3579) (five seasons)

16. Boston College: 35.4% (1948/5496)

Among the 11 teams who have been a member of the greatest conference in the land in each of the past nine seasons, only Wake Forest and Boston College have allowed a higher percentage of three-point field goals than UNC. Nonetheless, the very best (Duke) and worst (BC) figures are separated by only 4.3% - meaning only one additional three-point shot out of every 25 or so has missed the mark for the Devils’ opponents than the Eagles’.

The much more stunning aspect is the sheer volume of three-point shots and makes for Carolina’s opponents. UNC has allowed 1,119 more attempts from distance than the next team, Virginia Tech, over the past nine seasons. And it has surrendered 404 more made threes than the next team in that statistic, Florida State.

The Heels have never allowed fewer than 211 made threes in a season in this period, a total Virginia’s opponents have surpassed just twice. UNC hasn’t allowed fewer than 665 deep attempts (also 2013-14), again a total the Cavaliers’ foes have bettered just twice.

You may be thinking you can chalk that up to differences in style of play, which is mostly true. But before I even address that, there is another catch that brings these numbers slightly more into focus. Carolina has played six more games than anyone else (Duke) in the ACC since 2009-10, and a whole 52 more contests than regular-season-dwelling Wake Forest at the bottom – essentially a season and a half’s worth of extra outings. So here is the list again, this time somewhat arbitrarily ranked by fewest threes allowed per game (still our fave up top!):

1. Duke: 5.1/16.3 (331 games)

2. Virginia: 5.8/18.0 (305 games)

3. Clemson: 6.0/18.0 (294 games)

4. Louisville: 6.1/19.2 (137 games)

5. North Carolina State: 6.2/18.7 (309 games)

6. Maryland: 6.3/19.2 (168 games)

7. Georgia Tech: 6.3/18.8 (298 games)

8. Miami: 6.4/19.1 (309 games)

9. Pittsburgh: 6.6/19.3 (168 games)

10. Boston College: 6.7/18.8 (292 games)

11. Florida State: 6.9/20.4 (308 games)

12. Wake Forest: 6.9/19.9 (285 games)

13. Virginia Tech: 7.0/21.2 (298 games)

14. Notre Dame: 7.1/20.1 (178 games)

15. Syracuse: 7.4/22.8 (173 games)

16. North Carolina: 7.5/22.0 (337 games)

When the analysis is on a per-game basis, it really highlights how close most of the teams are. In general, an ACC team gives up between six and seven 3-point makes out of about 19 tries per contest. The outliers, or at least the poles, to avoid claiming statistical significance, are, obviously, Duke and North Carolina. The Heels have allowed 48% more successful long balls per game than the Devils on only 35% more attempts.

Syracuse’s figures are close to Carolina’s in 15^th, but the Orange famously plays a 2-3 zone, a style that notoriously invites 3-point attempts by the opponent. Notre Dame in 14^th also plays its own brand of efficient inside-out offensive ball that sees its foes attack the Irish the same way. Again limiting the comparisons to the most-tenured ACC squads anyway, Carolina has conceded 7% more made threes per game on 4% more tries than the next closest team (Virginia Tech) in the past nine years.

So, what gives? Why and how has the most successful team in the conference over the last decade been just letting folks rip it from deep? The Heels do realize those shots are worth 50% more, right? UNC’s answer, more or less: “We’ll worry about the ones you miss --- and the ones we do, too.”

Carolina has absolutely dominated the boards during coach Roy Williams’ tenure and thus the last nine seasons. It has led the ACC in total rebounds eight times and finished second to Maryland in 2012-13. The year before, the Heels finished eight boards per game higher than second-place North Carolina State and 15 better than last-place Boston College. Even in the disastrous 2009-10 campaign, the Heels paced the league with 42 rebounds per game.

Just in case you might contend that rebounding totals are crude numbers, UNC can back it up with data on rebounding margin and offensive and defensive rebounding percentage. The Heels have led the country in total rebounding percentage twice in the last nine years and have ranked in the top 10 of total rebounding percentage and offensive rebounding percentage four times each. They were top dogs in both categories during the 2016-17 national championship season, when Carolina also surrendered one made triple short of an even eight per game.

In fact, that is the very nature of the relationship. For decades, Williams has instructed his players to pack the paint and make opponents beat them by proving they can routinely drill long attempts. Rivals have obliged with the latter part of that statement, but they haven’t done a fantastic job with the beating part.

This all makes sense considering UNC’s style of play. First, a faster pace means more possessions, which means more shot attempts and more shot makes for both a team and its opponents. A fast-paced attack is aided by a sagging defense that swallows up almost all defensive rebounds and a transition offense that pushes the ball up court with strong outlet passes and running big men.

Carolina is the inverse on offense, putting constant pressure in the paint leading to low three-point numbers and astronomical offensive rebounding numbers. A natural assumption is that fast pace might indicate small-ball perimeter play, but the UNC big men are the fulcrum of both the fast-break and half-court offense.

Like all sports, basketball can be about trade-offs, and often times statistics don’t tell the whole story. If a team can impose its will against a bunch of pushovers down low, it will do so and attempt fewer triples. But if the opponent’s perimeter defense is Swiss cheese, then why bother going inside?

Unfortunately, that is exactly how most opponents view UNC. It can be pretty difficult to deal with as a fan, like when Clemson scored 21 points on seven threes with little resistance in the first seven minutes of an eventual 82-78 Tigers victory this past January. Again and again it seems like Carolina defenders are either too slow closing out on shooters, giving them too much space, or both.

This affliction may never be more apparent than during the upcoming season. Despite several promising reasons for optimism overall, a lack of bona fide playmakers off the dribble could lead Williams to demand an even faster pace. The trio of incoming freshmen --- Coby White, Nassir Little, and Rechon Black --- will play a big part in this attack, and what should be a well-conditioned trio of sophomore bigs will be equally critical.

I don’t expect Carolina’s three-point defense to be markedly better than it has been the last few seasons. If it makes you frustrated to the point of thinking Williams must be instructing his players to invite relatively uncontested shots from downtown, you just might be right.

Isn’t it possible to retain the general philosophy of welcoming opponent three-point attempts while tightening up the loose screws to yield a worse percentage? Well, sure. Virginia Tech has allowed the second-most rival three-point attempts in the ACC over the last nine seasons, yet has posted the sixth-lowest percentage. Heck, Syracuse and its zone has let opponents try the most perimeter shots per game, somehow still ranking fourth in percentage.

Then there’s a team like Virginia, whose coach Tony Bennett teaches a slow-poke style of play that simply won’t allow for a long ball barrage from opponents. Only Duke has allowed fewer enemy attempts from deep per game.

However, Virginia Tech has qualified for only two NCAA tournaments in that time (the last two seasons) and Syracuse and Virginia - though strong programs - can’t touch Carolina’s accomplishments.

The reason is simply that three-point defense might not be a huge indicator of men’s college basketball success, or at least Carolina’s success. The Heels’ two best defensive three-point percentage teams were in 2014-15 at 30.0% and 2013-14 at 31.7%. UNC ultimately bowed out in the Sweet 16 and second round of those respective campaigns, both of which would be classified as “just OK” Carolina teams.

On the other hand, the Heels enjoyed consecutive seasons playing in the final game despite a firestorm of three-point shots and makes by their opponents.

Nonetheless, Carolina’s third-worst three-point defense in the last 9 years was 34.6% in the 2012-13 season, which also happens to have been the only time in that period that UNC was both outrebounded overall (48.6 TRB%) and did not lead the ACC in total rebounds. So, the interaction between three-point defense and rebounding may be a little trickier than first meets the eye. It may not be a significant inverse correlation, but it certainly is not a positive one.

Subtle differences in percentages and raw numbers can sometimes scream a loud story. What is 2.4 opponent makes and 5.7 attempts per game, anyway? It’s the difference between the best three-point defense in the ACC (Duke) and one of the worst (UNC) --- two elite programs that achieve their greatness in vastly different ways.

Not every team can pull off Duke’s combination of raining threes offensively and preventing them on the other end. But the Heels have had at least an equal amount of overall success as the Devils. It can be frustrating to watch at times, but we do know one thing – it sure is winning basketball.