“You can’t teach height” - Red Auerbach
In the game of basketball, especially in the NBA, where the game is played “above the rim”, one of the most important talents is height - out of two players who possess the identical skill set, the taller player has the advantage over the smaller one.
RunRepeat team decided to put height under the microscope. The initial goal and purpose of this research was the evolution of height throughout the NBA history. But what we have discovered is that height is a great tool to describe the evolution of the game.
The results of our research show that, even by using the most fundamental and basic statistical categories, when you add the evolution of height into the equation, you’ll be able to see how the game has changed over the years.
Our research results are divided into five sections - explore them and discover how the game evolved through the prism of height.
- While the average height in the NBA has been revolving around 6'7'' for the last 30 years, the league has witnessed some big changes in the way how height is distributed and utilized in the game.
- Since 2011, after almost four decades, height/weight ratio is trending upwards - players are getting more agile and quicker to fit with the modern beyond-the-perimeter game.
- There is a trending decrease in height difference between the positions - centers and point guards have never been closer in terms of height.
- Numerical supremacy of players taller than 6'9'' is finished after 3 decades - this is the era of 6'3''-to-6'9''-ers.
- NBA big-men have experienced the biggest changes in the recent years, especially in shooting distribution.
- From 2011/12 to 2017/18, NBA power forwards increased their per game 3PA by 327%.
- Over the same period, 7-footers increased the share of 3-point shots in total FGA from 4,6% up to 21.3%.
- Aside from the offensive rebounding, every statistical aspect covered in the research is heading towards the equal distribution among different height ranges.
- In 2017/18 season, SFs and PFs averaged the same amount of assists for the first time in 5 decades.
- Although declining in number, players taller than 6'9'' are contributing with the most Win Shares in the league, and have significantly separated themselves from the rest over the past several seasons.
- Rookie data more explicitly confirm the trends in height distribution.
- Rookie big men have become significantly lighter in the past few years - designed to fit into the perimeter-oriented game.
- International players in the NBA are taller (on average) than USA natives, from point guards to centers.
- Foreign big-men had a big part in the evolution of the modern game.
Table of contents
1. Height changes throughout the NBA history
As the introduction quote from the legendary Celtics coach Red Auerbach suggests, NBA coaches have quickly realized the advantage of being taller than the opponent - the average height in the league was growing steadily for the first 4 decades.
And while the growth was linear (even exponential in the early years) up until the mid-80s, height took a steady 6’7'' average ever since.
Although the average height has been stagnating for the last 3 decades, there have been some interesting changes in various height distributions and, naturally, game style.
Just looking at height averages by position, we can see that the difference between Cs and PGs last season has been the lowest in the past 42 years, and has been additionally reduced by 10% in the last 3 seasons.
Unlike height, average weight has undergone significant changes since the mid-80s.
NBA players' average weight was constantly growing, peaked in 2010/11 season, and have been declining ever since.
The average weight difference between the Cs and PGs has decreased by 13% in the last 6 seasons. Also, it’s noticeable that in the last few seasons C, PF, and even SF positions are getting lighter, while PGs are increasing their weight average.
Displaying combined height and weight changes, with height/weight ratio, sums up the evolution of players' physical attributes over the years.
This chart is a clear indicator of the evolution of athletic requirements in the NBA. Since the 80s, while the average height has been stagnating, the average weight was constantly increasing, as players got physically stronger in order to compete in a game that became extremely physically demanding.
However, since 2011/12 season, the ratio went the opposite way. Tall players are becoming lighter and lighter, as the game switched from the paint out on the perimeter, promoting speed and agility as the most important factors for the trending small-ball offense.
The ideal small-ball lineup would consist of 5 guys with the same physical attributes and skill set - complete interchangeability.
So it’s not strange that, since 2012, players whose height is between 6'3'' and 6'9'' increased their number in the league by 20%. At the same time, players on the top and the bottom of height scale are stagnating or decreasing their population numbers in the league.
Looking at the historic share of height ranges in the NBA, it seems that we're heading back to the 60s and 70s, when players in the range between 6'3'' and 6'9'' were dominant in number.
2. Shooting evolution by height
Firstly, looking at the overall FG shooting, the FG distribution has been following height evolution closely throughout the league history, with height weighted by FGA being slightly below the average height for the last 30 years.
What this means is that the players shorter than the league average have been taking most of the FGA in this period. However, in 2017/18 season, these two heights have equalized.
On the other hand, taller players have proven to be more accurate FG shooters.
Contrary to FGA, height weighted by FG% has always been above the league average, and this difference has become even more noticeable since the 2000s.
The difference in FG% between players taller than 6'9'' and the rest has started increasing ever since the 80s, especially over the last decade - in 2018/17 season it was on a historic level.
NBA centers have noticeably separated themselves from the other positions in this category. This difference has been constantly increasing since the new millennia, despite the fact that the centers have significantly increased their 3-point attempts in the last few seasons (we'll talk about that soon).
Let’s see what height can tell about 3-point shooting. Since the introduction of the 3-point line in 1979-80 season, there have been some dramatic changes in 3-point shot distribution.
While at the beginning it was a short player's exclusive privilege, taller players have gradually adapted their game and started utilizing 3P shooting as a weapon. This is why height weighted by 3PA has never been closer to the average height than last season, and the trend is expected to continue in the future.
It's the same story with the share of 3-point shots in the total FGA, which the evolution of height weighted by the 3PA/FGA ratio clearly suggests.
Breaking down to height ranges, players from all ranges have significantly increased their 3PA over the years. While this trend is expected for players who play beyond the perimeter by default, it's the players taller than 6'9'' who experienced a real metamorphosis in this field.
In 2017/18, 21% of the NBA 7-footers' field goal attempts came outside of the 3-point line. Who could predict this only 10 years ago?
Looking at the positions distribution of 3-point shots, a real revolution has started several seasons ago.
In 2011/12 season, PFs were attempting 0.84 3-pointers per game. Last season, they stopped at 2.75 – this is a 327% increase over the course of 6 seasons and nearly a double increase in the last two seasons only. Modern PFs are taking nearly as much 3-point shots as PGs and SFs - stretch four is the word.
During the same period, Cs have come up to the 0.88 3PA per game - in the modern era, every NBA position is heading towards at least 1 3-point shot per game.
Also, in the 2017/18 season, 13% of shots that NBA centers took were 3-point shots. And what to say about PFs - every third shot is beyond the arc, same rate as PGs.
3. Basic stats evolution by height
Let’s start with the rebounding. On a league-wide level, offensive rebounding averages are getting lower and lower every season, while the average height weighted by offensive rebounds is moving away from the average height.
Looking a bit deeper, only big-men (players taller than 6'9'') have somewhat maintained the offensive rebounding rate through the years, while the others are declining in this area.
Position-wise, Cs are the only ones left with the respectable offensive rebounding average. PFs are facing 40% decrease in the last 6 years. When you put the game-changing perspective in the story, the results are not surprising.
It’s a bit different story with defensive rebounds, where things have been more stagnant over the last 30 years.
Looking at the trend, defensive rebounds have a more stable distribution between height ranges.
Especially in today’s game, where 4 or 5 guys on the court are playing beyond the arc, defensive rebounds are the most evenly distributed between positions since this stat has started recording, especially among guards and forwards.
Assist evolution through height tells another interesting story. The results show that in this segment we’re also witnessing a tendency of equalization of weighted height (by assists in this case) and the average league’s height.
Breaking it to height and position ranges, big-men are the only ones who are increasing their assist rate in the last several years.
In fact, in 2017/18, SF and PF have averaged the exact amount of assists (the first time in the last 5 decades), and Cs are getting pretty close. Aside from PGs, other positions are very close to each other in assist averages.
Steals and blocks aspect is also heading towards the equalization of weighted heights with league average – blocks' height is trending down, while the steals' height is rising.
Both trends are very understandable considering that the game is playing as far from the basket as ever.
One more interesting research result is the Win Share evolution. After the big-men domination of the game in the 60s and 70s, ever since the 80s we’ve witnessed the equal distribution of Win Shares among height ranges.
Height weighted by Win Shares reflects this trend. However, in the last few seasons, big men have yet again separated themselves from the others.
This is the best example of the evolution of the big men - while their game has suffered the most changes with the small-ball revolution, the ones that have “survived” the and adapted are proving to be the most valuable to their teams in terms of Win Share contribution.
Players in height range above 6'9'' have averaged the most Win Shares throughout the league’s history, and in the last few seasons, they’ve additionally widened the gap.
With this in mind, for the first time since the 83/84 season, there is a noticeable difference in Win Share averages between the Cs and the rest of the league.
4. Rookie height evolution
Rookies’ data are an interesting tool to examine the league's year-to-year tendencies. The data are much more “unstable” and fluctuate more on a yearly basis, but they are more precise in explaining the league’s current trend.
Looking at the rookie’s position height changes, there’s a noticeable trend in the last few years among the shortest and the tallest positions.
The centers have never been shorter in the last 44 years, and in 2017/18 season rookie Cs and PFs had almost the identical average height, which hasn’t ever happened. PGs, on the other hand, have never been taller in the league’s history.
Looking at the height/weight ratio, the new-requested emphasis on speed and agility of the players, especially the big men, is immediately noticeable. Rookie Cs and PFs are on the highest height/weight ratio rate in the last 28 seasons, they have been on the equal scale in the 2017/18 season, and the closest in this aspect to SFs and SGs in the last 20 years.
5. International players height evolution
The last aspect covered in this research is about international players. Since the 1985-86 season, which was the first season with 10+ international players in the league, they have become an integral part of the NBA, and are constantly growing in numbers with each passing season.
The reason why exploring foreign players could be interesting is apparent right from the height evolution chart.
While the average NBA player height was pretty much revolving around 6'7'' since 1986, international players have suffered more dramatic height changes. In the beginning, the NBA was “accepting” only international big-men in the league.
And even when the league expanded height range of “acceptable” international players, it’s noticeable from the charts that they’re still taller than the league’s average, although the gap is narrowing over the years.
Looking at the number of foreigners in the NBA, although the average height is in declining, international big-men are still the most wanted in the league.
Overseas countries are holding a monopoly over the 7-footers in the NBA - over 50% of the players above 7'0'' were coming from abroad over the last 20 years.
It’s pretty easy to conclude that the center position is on demand when international players in the NBA are of concern.
Today, more than 40% of the NBA centers are not USA citizens. However, this number is declining over the last couple of years. Why?
Over the years, big men coming from abroad, particularly from Europe, have proved to be more skillful with the ball in their hands. They’re educated to play a team basketball, share the ball and learn to read the game.
This is visible on the charts – since the new millennia, when the centers slowly but surely started getting more involved in the flow of the game, by setting pick&rolls and “migrating” outside of the paint, they needed to develop a new skill set, one that the European centers already possessed.
In some way, it was the international big men who made the small-ball revolution possible. In the last few years, we’re facing a slight decline in the share of foreign centers among the NBA players, as the USA centers started to catch up with the overseas colleagues, skill-wise.
- Although the first NBA season was 1946/47, the results displayed in this research are starting from the 1951/52 season, due to the incomplete data for the previous seasons.
- The exceptions are 3-point shooting (introduced in 79/80), off/def rebounds, steals, and blocks (started recording from 73/74).
- For the international players segment, season 85/86 was chosen as a starting point, since it was the first season with more than 10 international players in the league.
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