How Important is the Three-Point Shot in Today’s NBA?

Derick E. Hingle / USA TODAY Sports

For just about as long as “the basketball blogosphere” and “basketball Twitter” have been things, we’ve heard it bandied around in both fora that the NBA is increasingly becoming a three-point shooting league. Indeed, this notion is based in statistical reality — the league’s collective style of play today is dramatically different than it was at the turn of the millennium, and the outside shot is largely responsible for that. In the 2000-01 season, the average NBA team attempted 1,124 shots from long range; this year, the Minnesota Timberwolves are dead last in shooting the three, but even they’re on pace to launch 1,225 attempts. The Los Angeles Lakers, whose coach is fundamentally opposed to the shot, are careening toward a season total of about 1,600.

But simply to ask “How many threes are teams taking?” is too boring a question. It’s more fun if you take it one step further. What’s interesting is to explore not just raw numbers of shot attempts, but also how important those attempts are for teams that seek to create efficient offense. In other words — how integral is the three in today’s game?

To answer this question, you need two main variables. One is percentage of three-point attempts, and the other is offensive efficiency. For reference, the average NBA team this season has attempted 26.7 percent of its shots from long distance, and they’ve put up 105.8 points per 100 possessions, according to data from basketball-reference.com.

If you break it down team by team, looking at how prolific three-point shooting translates to scoring for each of the 30 squads in the NBA, you get a scatterplot that looks a little something like this:

You’ll notice a definite upward trend among these 30 data points three the more often teams attempt threes, the more they score. The bottom-right corner is completely empty — in plain English, not a single NBA team this year has taken 30 percent threes or more and been bad offensively. All nine teams above that 30 percent mark have ranged from the fairly solid (Houston, Portland, Phoenix) to the incredibly awesome (L.A., Toronto, Golden State, Dallas).

That’s the “plain English” version. But what’s cool is that you can actually quantify the necessity of the three-point shot in any given season. Look at the best-fit line running through the middle of these 30 orange points. You’ll notice there’s an equation for the line in slope-intercept form, and the slope is listed as 27.088. In other words, that 27.088 number is a statistical measure of how useful the three-point shot has been in 2014-15. For every 1 percent more three-pointers taken, the average team improves by 0.27 points per 100 possessions. That’s a significant number — look at where Utah is on this graph, and look at Portland. The Blazers take three-pointers about 6 percentage points more often than the Jazz do — as a result, they score about 1.5 points more per contest. In the long run, those points are winning the Blazers ballgames.

Now let’s go one step further. If we know that in 2014-15, the 3-point shot is worth 0.27 points per 1 percent, how does that figure compare to the same number in past seasons? We’re told that the 3-pointer is becoming more and more meaningful every year, right? Do the numbers back that up?

Here’s the same chart, only using the 2013-14 data this time.

Unsurprisingly, this one looks fairly similar. Again, the Clippers and Mavs are awesome; again, the Suns are above average as well. Again, the Rockets take the most threes in the league and are a good, but not fantastic, offensive team. The main differences you see here are understandable ones — the Heat were in the top-right last year because they had LeBron James (and Ray Allen), and the Thunder were there because they had a healthy Kevin Durant shooting more than Russell Westbrook and taking a lot of threes.

And again, there’s a best-fit line that slopes way, way upward. In fact, it’s even steeper this time — 42.759! That’s a tremendously strong trend. Look at the Wizards and Knicks, both hovering right around expectation — New York shot the three about 5.5 percentage points more than Washington last year, and that led to 2.5 more points per game. A huge difference.

(It’s worth noting at this juncture — there is a ton of noise that goes into these calculations. Just one small change to this data set can throw off the math in a big way — for example, the mere existence of the tanking Sixers and their historically terrible offense is a major confounding variable in the 2014-15 calculus. If you pretend for a moment that Philly doesn’t exist, the entire graph changes dramatically and the slope increases by about 6.5 points. Likewise if you erase Nicolas Batum’s shooting slump and give Portland the same stellar efficiency numbers they had last year.)

Having said that, you can still find some interesting trends if you zoom out and look at a large enough sample of the data. And thanks to the shooting numbers available on basketball-reference, you can actually go back and scrape together three-point stats and efficiency ratings for every team in every season since the turn of the century. All in all, the long-term trend is undeniable — the three-point shot has become more important in recent years. Here’s the 15-year trend:

The numbers are a little wonky (you might as well throw out the bizarre, lockout-shortened 2012 season), but the bottom line is that the NBA has had several of its most three-point-dependent seasons in recent years. The league-wide “three factor” went from 20.6 in 2009, to 27.7 in 2010, to 35.2 in 2011 before hitting record levels in the last couple of seasons.

But it’s not just the slope of the line that matters. To answer the “How important are three-point shots?” question, the other variable you need to consider is the coefficient or determination, or “R squared” value. You can read all about the concept here if you’d like, but the gist is this — R^2 measures how well the data fits that best-fit line. In other words, how strong the relationship is between shooting 3s and cranking out good offense.

Here’s how the R^2 values have changed over time:

All in all, the graph looks pretty similar to the one shown above — meaning that when 3s translate to good offense, they really, really do, and when they don’t, they don’t. League-wide 3-point shooting peaked in 2013, when the R^2 value hit a record high of about 0.36. In other words, this means 36 percent of all variation in ORtg is explained by the variation in three-point shooting. That’s… um, a lot.

Here’s the chart of all 30 NBA teams in 2013 – when, incidentally, the slope of the best-fit line also reached an all-time high at just over 47.7:

The correlation between threes and efficient offense here is uncanny. The vast majority of the league just two years ago was shooting the three less than 25 percent of the time — and all those teams are jam-packed in the bottom-left corner of the graph. Only a select few squads were ahead of the curve, and it’s not rocket science to explain why — they had the personnel to shoot the lights out. The Knicks had Carmelo Anthony in a career year. The Rockets were in year one with James Harden leading the offense. The Clippers had Chris Paul and a veritable army of shooters around him. The Thunder had Durant. The Heat won a championship with a new and improved offense that thrived with shooting and spacing. Fittingly, the most memorable shot of the year was a corner three-pointer that Allen made to tie Game 6 of the NBA Finals against the Spurs.

We’re now in a golden age of three-point shooting — an era in which, every year, the teams that shoot the best from downtown rise to the top of the pack offensively. There are a couple of reasons for this. One is the way defenses have adapted over the years – because every team is anchored by a “rim protector” type and every team prioritizes quick, long guys who can adequately defend pick-and-rolls, you need to have good spacing to break down the advanced defenses in today’s league. The three has become a necessity.

The other reason for our modern three-point age? Simple — the personnel dictates the style of the game. We’ve never had fewer dominant big men in the game than we do today. Shooters, meanwhile, are en vogue. There are far more Durants, Hardens, Stephen Curries and Kyle Korvers than there are Shaquille O’Neals. Today? The NBA is a three-point shooting league. But tomorrow, if DeMarcus Cousins were to discover human cloning technology and copy himself five times? The game might swing back the other way, pronto.

For the moment, there’s no doubt that the three reigns supreme in our league. Baxter Holmes, who covers the Lakers for ESPN, noted in the wake of Byron Scott’s anti-three comments this preseason that seven of the last eight Finals winners have led all playoff teams in three-point attempts and makes. He’s right — and the preeminence of outside shooting isn’t just a postseason thing, either. It’s an all-year thing. In fact, that’s more the case now than it’s ever been.