How Defense Influences Three Point Shooting

Dateline: 04/03/97

The NBA All-Star Three-Point Shootout presented a unique opportunity to get a feel for how important defense is to lowering field goal percentages. In that contest, eight players competed against a 60-second timer to make as many of 25 three pointers as possible. There was no one guarding them. The only pressure was in their mind.

Steve Kerr, the Chicago Bulls' three-point marksman, won the contest by hitting 17/25 shots in the final round, including the five money balls, which counted for additional credit. Kerr's percentage in that final round was an astounding 68%, ridiculously high even for him, the NBA's career leader in three-point shooting percentage. Through the contest, Kerr's percentage was 64%, hitting 48/75 shots through three rounds. This, too, is much higher than his 47% career figure and his 45% shooting this season.

This implies that, even though Michael Jordan draws substantial defense away from Kerr, it still isn't the same as having no defense on Kerr. Roughly, it looks like Kerr's percentage goes up about 20%.

For the other players in the contest, the improvement was not quite as large. Only Sam Perkins shot worse in the contest than he does during the regular season, but no one improved as much as Steve Kerr. Below, I present a table showing the players' shooting percentages in the Shootout and their established three-point percentages (uses this season's numbers, except for Legler who has been injured).

Comparison of Shootout Percentages to Game Percentages

Shootout % Established 3pt %
Kerr 64% 45%
Legler 59% 52%
Williams 53% 41%
Rice 48% 47%
Stockton 44% 42%
Ellis 40% 35%
Mills 44% 42%
Perkins 32% 41%
Average 52% 42%

From this, we can estimate that players increase their three-point shooting percentage by about 10% without defensive pressure. It is not a great study, but it gives us something to grab onto and think about when watching a defense rotate onto Jordan and leaving Kerr open at 23 feet.

As a final comment on this, check out the runs of makes and misses that the players had in the contest. Specifically, notice that the longest run of made shots was nine by Kerr in the finals. This "hot streak" is completely normal for someone who makes 64% of their shots...

Remember Those Low Scores?

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At the start of the season, people were complaining incessantly about the scores of games being low. Offenses were poor and the pace was slow.

Now that the season is nearly complete, the complaints have died down and scores have climbed up. After a month of the season, teams were scoring 94.5 ppg and their offensive efficency was poor, scoring only 101.9 points per 100 possessions. Now teams are scoring 96.4 ppg and their efficiency is up to 104.4 points per 100 possessions.

Both these figures are still below last year's figures of 99.5 and 105.9, so something is probably wrong, but not disastrously wrong as many might have thought at the start of the season.

What is most wrong is shooting from two point land. Though three point shooting percentages have gone up again, teams are shooting nearly a full percentage point below last season. (Early on, there was a distinct rise in turnovers, probably due to the referees calling traveling and carries a lot more than they had in the past. This effect seems to have diminished as turnovers are up only slightly from last year.)

There are a couple strange things about this drop in shooting percentage. First, foul shooting has not dropped off significantly from last season. So perhaps defenses have improved rather than offenses getting worse. Second, the game has slowed down as teams take more time looking for good shots. At least this has been the theory. Teams pass up relatively lower percentage shots while the shot clock is high as they work it around for easier shots. Perhaps teams have gone past the time where they feel safe and are now being forced into rushed shots with the clock running down. Violations of the 24-second clock have been increasing steadily over the past several years, but not to such an extent that it appears to be significant. It may be more important now.

Regardless of the reasons, which one can argue about forever, there has been a decline in offense this year. The NBA's popularity climbed as offenses improved through the '70's and '80's.