The miserable showing by the US Olympic basketball team has people talking about the decline of shooting in the NBA. It’s certainly true that this team can’t shoot. But is offensive efficiency and skill really in decline around the league? It’s an appropriate time to unveil another of my long-standing research projects: a statistical history of offensive efficiency and tempo in the NBA. My apologies if someone else has done this stuff before, but I got tired of trying to find it somewhere; tip of the hat to Basketball-Reference.com for the numbers.
I’ll run these in table form, decade by decade. The first four columns of the chart should be familiar enough: the leaguewide averages for team points per game (P/G), shooting percentage on two-point shots (2%), on three-point shots (3%), and on free throws (FT%). A key stat I use here is Points Per Field Goal Attempt (PPFGA), developed by John Hollinger of the Basketball Prospectus; the formula is (P/(FGA+.44(FTA))). Basically, Holinger started by assuming that a free throw is worth 1/2 of a field goal attempt (e.g., you get two shots for two points instead of a single field goal attempt), then cut the ratio from .5 to .44 based on an analysis of how often guys shoot an extra free throw after hitting a bucket, for a technical foul, etc. I use the denominator of this formula to estimate the number of team shot attempts per game (FGA/G). The last three columns seek to break down the components that go into offensive efficiency above and beyond the shooting percentages: the percentage of the league’s points that were scored at the line (FT/P), the frequency of free throw attempts per field goal attempt (FGA/FTA; a higher number means less free throws), and (since 1979-80) the percentage of shots that were three-point attempts (%3).
I’ve listed league expansion and contraction under “Major Rules Changes,” but I’m sure I’ve missed some actual changes in the rules that had some significant effects. Also, I haven’t set out the blow-by-blow extension of the schedule; the NBA schedule rose gradually to 72 games in 1953-54, then went up to 75 in 1959-60, 79 the following year and wound up at its present 82 in 1967-68. I also haven’t done a similar table for the ABA, for a variety of reasons; maybe another day. Let’s begin:
The 1940s
Major Rules Changes: 1947-48, league contracts from 11 teams to 8; zone defenses outlawed
Season |
P/G |
2% |
3% |
FT% |
PPFGA |
FGA/G |
FT/P |
FGA/FTA |
%3 |
1946-47 |
67.8 |
.279 |
N/A |
.641 |
0.693 |
103.9 |
23.4 |
3.75 |
N/A |
1947-48 |
72.7 |
.284 |
N/A |
.675 |
0.674 |
107.9 |
25.1 |
3.56 |
N/A |
1948-49 |
80.0 |
.327 |
N/A |
.703 |
0.781 |
102.4 |
27.5 |
2.83 |
N/A |
The NBA traces its official records back to 1946-47, although the league was known as the BAA (Basketball Association of America) for the first three years prior to a merger with another professional league. To the modern eye, a league-wide field goal percentage around .280 is almost inconceivable, although to the novice basketball fan at the time it may have seemed to make it easier to grasp basketball statistics (see! they’re just like batting averages!). As you can see from the above and the seasons of the early 1950s, however, the offensive skill level of the league was improving rapidly as the league gathered the nation’s best basketball players; look at the 60-point increase in the league’s free throw percentage in a two-year span. Free throw percentage is a good barometer of basic shooting skill, since free throw shooting is basically just man vs. basket, with no adjustment for the level of competition. The pace of play reached a pre-shot-clock high of 107.9 shot attempts per game in the league’s second season, when teams played just a 48-game schedule.
The 1950s
Major Rules Changes: 1951-52, size of foul lane doubled from 6 to 12 feet; 1954-55, shot clock introduced; 1957-58, ban on offensive goaltending
Season |
P/G |
2% |
3% |
FT% |
PPFGA |
FGA/G |
FT/P |
FGA/FTA |
%3 |
1949-50 |
80.0 |
.340 |
N/A |
.715 |
0.820 |
97.6 |
29.5 |
2.52 |
N/A |
1950-51 |
84.1 |
.357 |
N/A |
.732 |
0.855 |
98.3 |
29.1 |
2.50 |
N/A |
1951-52 |
83.7 |
.367 |
N/A |
.735 |
0.877 |
95.5 |
29.2 |
2.43 |
N/A |
1952-53 |
82.4 |
.370 |
N/A |
.716 |
0.887 |
92.9 |
31.2 |
2.15 |
N/A |
1953-54 |
79.5 |
.372 |
N/A |
.709 |
0.885 |
89.9 |
29.4 |
2.28 |
N/A |
1954-55 |
93.1 |
.385 |
N/A |
.738 |
0.911 |
102.2 |
28.5 |
2.41 |
N/A |
1955-56 |
99.0 |
.387 |
N/A |
.745 |
0.916 |
108.1 |
28.6 |
2.40 |
N/A |
1956-57 |
99.6 |
.380 |
N/A |
.751 |
0.899 |
110.8 |
27.9 |
2.56 |
N/A |
1957-58 |
106.6 |
.383 |
N/A |
.746 |
0.898 |
118.7 |
26.8 |
2.66 |
N/A |
1958-59 |
108.2 |
.395 |
N/A |
.756 |
0.915 |
118.3 |
25.4 |
2.82 |
N/A |
Basketball in the Fifties, especially early in the decade, was a bruising business, as earthbound forwards and centers dominated the game. The level of violence in the game reached a pinnacle in the 1952-53 season, with one foul shot for every 2.15 field goal attempts and a record 31.2% of all points being scored at the line. Perhaps the archetypical player was Dolph Schayes, who shot 40% in a season just once (.401 in 1959-60), but averaged nearly 8 free throw attempts per game for his career while shooting .849 from the line, and averaged 12 or more rebounds a game 11 years in a row. Bob Cousy debuted in 1950-51, and revolutionized the game by being the first true point guard, but took some time to foster imitators; Bill Russell arrived in 1956-57, although black players would not become a common fixture for several more seasons. You can see the immediate and dramatic impact on tempo of the shot clock, as well as the fact that it was introduced to arrest a decline in the pace of the game.
Continue reading BASKETBALL: Shooting By The Numbers