Why Have NBA Offenses Been So Good In The Bubble?


In the days leading up to the resumption of the NBA season, there was one school of thought about the quality of basketball we would see. “It’s gonna take time for your offense to come,” said TNT analyst Reggie Miller during the first quarter of the ragged Lakers-Clippers bubble opener on July 30. “And that’s why I think defense will be ahead of your offense.”

But the exact opposite proved to be true in the seeding games. The 22 teams in the bubble averaged 113.17 points per 100 possessions, according to Cleaning the Glass, up from the 111.95 they averaged before the league shut down in March.1

Offense was already on pace for historic levels before the COVID-19 shutdown. Instead of reversing that trend, as Miller and others predicted, the seeding games in the bubble dramatically accelerated it. In fact, the average offensive efficiency in half-court possessions jumped from 95 before the shutdown to 98.7 in the bubble. In situations where the offense and defense were on level playing fields, the offense gained more of an edge, not less.

It’s understandable why Miller and other analysts got it so wrong. They were just following recent NBA history. While there’s no parallel to a four-and-a-half month in-season break caused by a global pandemic, the labor disputes of 1998 and 2011 at least shared some characteristics with 2020’s stoppage. In both ensuing seasons, the average offensive efficiency fell dramatically from the previous campaign before rebounding the following year.

Offense dipped after previous work stoppages

Average league metrics for regular seasons following work stoppages in 1998 and 2011 vs. the seasons immediately before and after

Season Offensive Rating Defensive Rating True Shooting% effective FG%
1997-98 105.05 105.01 52.38% 47.83%
1998-99 102.22 102.18 51.18 46.59
1999-00 104.05 104.04 52.29 47.83
2010-11 107.26 107.23 54.15 49.85
2011-12 104.59 104.60 52.70 48.73
2012-13 105.84 105.84 53.47 49.66

Source: Basketball-Reference.com

Like those post-lockout seasons, this year’s COVID-19 interruption featured a monthslong layoff with no clear end date, separation from team workout facilities, a shortened preseason and a compressed schedule to fit as many games in as possible. “Most of these players don’t have their legs yet,” Miller said during the same segment. “Remember, four-and-a-half month layoff! And now you’re shocking, you’re jolting the body.” The evidence seemed clear: Those shortcomings would affect offenses more than defenses.

So why did the opposite happen in 2020? Two reasons: Defenses couldn’t stop fouling, and shooters couldn’t stop missing.

Indeed, referees blew the whistle a lot more often after the restart than before. Every type of foul was called more often in the bubble. There were more shooting fouls drawn, but there were also more freedom of movement infractions that occurred before the shot. Even offensive fouls, such as illegal screens, were whistled more often. Referees didn’t discriminate, and that meant teams spent nearly 30 percent of their bubble possessions in the penalty, compared with 26 percent before the break.

Fouls are way up inside the bubble

Fouls committed per game in the bubble vs. before the 2019-20 regular season was suspended

foul category Before the break Since the restart Difference
Shooting 19.47 20.92 +1.45
Other personal fouls 13.64 14.88 +1.23
Loose ball 2.34 2.89 +0.55
Charges 1.20 1.43 +0.23
Other offensive fouls 2.75 3.60 +0.85
Technicals 0.72 0.75 +0.03
All other fouls 1.05 1.33 +0.28
Total 41.17 45.80 +4.63

Regular-season stats only.

Source: PBP Stats, NBA WOWY

The average free-throw rate – free throws made per 100 field goal attempts – jumped from 20 before the shutdown to 22.8 in the bubble seeding games, a mark unmatched over a full season since 2010-11. Free throws, which had been steadily dropping in the 3-point era, made a comeback.

The unique bubble environment produced many theories for the increase in foul calls. Without fans, referees could more clearly hear the contact they would otherwise miss on bang-bang plays, not to mention the complaints from players and coaches. Players needed time to regain their conditioning after the layoff, and tired players tend to commit more fouls. The refs themselves were out of rhythm and needed time to readjust to the speed of the game.

There’s a degree of truth in each of those explanations. As Seth Partnow of The Athletic noted, the league’s collective free-throw rate sunk back to normal levels in the second week of the bubble after skyrocketing early on. Everyone just needed time to adjust to the new normal.

Yet offense continued to rule even once the whistles became less frequent. At the same time foul-drawing fell back to earth, shooting accuracy shot through the ozone layer. The league-average effective field-goal percentage rose a full point in the bubble, and it was 1.7 percentage points higher than the pre-bubble regular season in the final week of games alone. This again bucked the trend of the two post-lockout seasons, during which shooting accuracy fell dramatically before bumping back up again.

Those in the league were less surprised that the bubble environment proved to be a shooter’s paradise. “It’s the same court every night,” said Rockets coach Mike D’Antoni. “You get your shooting, depth perception and all that.” The absence of fans not only eliminated distractions but also improved players’ sight lines. As Dallas Mavericks guard Tim Hardaway Jr. told The Ringer: “You can’t see through the backboard, shooting-wise, since it’s blacked out.” And don’t underestimate the impact of the benches moving farther away from the sidelines, costing teams the ability to scream at opposing shooters.

All of those factors certainly contributed to the rise in 3-point shooting. Bombs from downtown accounted for a higher percentage of overall shot attempts in the bubble, and players made more of those shots than before. In one sense, the defense didn’t matter as much as the unique environment itself. Players shot and made a higher percentage of wide-open looks, but they also made a higher percentage of heavily contested looks.

Shooters have been better regardless of defense

Frequency and field-goal percentage of shots taken by defender distance, in the bubble vs. before the 2019-20 regular season was suspended

Closely defended Wide-open
Frequency FG% Frequency FG%
Since the restart 8.46% 48.67% 22.56% 42.72%
Before the break 8.71 46.24 21.96 42.01
Difference -0.25 2.43 0.60 0.71

Closely defended shots come when a defender is within 2 feet. Wide-open shots come when the closest defender is at least 6 feet away.

Regular-season stats only.

Source: NBA.com

In another sense, though, the defense really was behind the offense in a way that wasn’t specific to the environment. Better sight lines may explain why shooters made more corner threes, for example, but they don’t really explain why they took more corner threes. Defenses may have overreacted to dribble penetration, violating the cardinal rule of never helping off the strongside corner.

Those are mistakes brought on by many of the same forces that caused the increase in foul calls. Tired players make mental errors, especially when trying to process the many threats today’s spread offenses present. After all, when faced with a pandemic that requires social isolation, it’s a lot easier to fine-tune a jump shot than a coordinated defensive scheme that requires precise movements and teamwork.

When put that way, the league’s post-COVID-19 offensive explosion shouldn’t be a surprise. Jolting the body after a four-and-a-half month layoff may have adversely affected offenses in the past, but that was before the 3-point revolution transformed the sport and forced defenses to cover more ground with the same number of players. Today’s style of play is nothing like the one that dominated most of NBA history. Why should the same post-layoff historical standards apply?

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