Changes in NBA Players over time
I regularly find myself in arguments about the NBA. And it's not unusual for one of the participants to reference some characteristic of the league that has supposedly changed over time.
The particular claim isn't necessarily controversial - in fact on many occasions it's something everyone involved agrees on - but the evidence is usually anecdotal and subject to all kinds of bias.
In any case, I've had it in the back of my mind to actually try to quantify many of these things at some point. What follows is the very first step in that direction.
There are many different perspectives that one could but pursue I will start with how the players have changed physically.
Using data available from Basketball-Reference.com I made a few simple boxplots in R to show the evolution of players' heights and weights at different positions over time.
For players listed as guards, it can be seen that the median height has stabilized at 6-3 since the 1970s with the higher end of the guard range creeping up slightly since then. The median weight for a guard in the NBA is still
inching up however.
(That 5'3", 114 lbs player in the 1960s was Penny Early. According to
this, Penny was the first licensed female horse jockey in the country but the other jockeys refused to race against her.
After signing a contract with the Kentucky Colonels of the ABA, she threw one successful inbounds pass before the Colonels called a time out and substituted her.)
For players listed as swingmen on the other hand, median height from the 1980s to the 2000s was an inch taller than in the 1970s and are an inch taller still for the decade currently in progress. Also, like the G
category, the weight of the typical player listed continues to rise steadily over time.
Players listed as forwards have climbed steadily in height and weight over the lifetime of the league as can be seen below.
Big men that are listed as both forwards and centers have also been getting taller and heavier steadily over time.
The center position increased in height noticeably over the first couple decades of the league but the 25th to 75th percentile range seems to be very stable since the 1980s. In terms of weight the median player from the 1990s to
the present is about 10 lbs heavier than his 1980s counterpart.
It seems to me that, in the 1950s the variation between the heights at the various positions was much less than in subsequent decades. The center position seems to have plateaued both in height and weight over the
last 25 years or so and the taller forwards are now gaining in terms of height and to a lesser extent in terms of weight. Players listed just as guards have had a stable median height for 40+ years but the bigger guards and swingmen
are getting taller. In the aggregate, perimeter players do seem to weigh more each decade thus far.
- There are 7 different positions listed G,G-F,F,F-G,F-C,C-F,and C (the individual player pages give more granular information such as "Point Guard" but I'll avoid that for now). F-G and G-F are treated as interchangeable
as are C-F and F-C.
- I've grouped players by decade. A player is included in the dataset for a decade if their start or end dates are in the decade or their playing days contained the entire decade. Thus some players may be included in the data for
- There is only one height and weight in the main directory for each player. This is the height and weight used for all decades that player may count toward.
- Ideally, a weight for each player each season would be available. I don't think this hurts the ability to see general trends very much as the typical player seems to have a short career (Median: 3 seasons, Mean: 5.126 seasons)
and it seems reasonable that their weight would not change dramatically over that time.
A moderate amount of extra effort could have allowed this to be done for a greater granularity of positions e.g. PG, SG, SF, PF, C.