This week's mini-project is composed of contributions from Eashan Kothari and Brian Li. Eashan looked at various aspects concerning the style of play in the bubble, while Brian seeked to determine if three point shooting was significantly different in the bubble.
Eashan Kothari:
As our time in the NBA bubble has reached a conclusion, we have seen some of the oddest occurrences in this new and unprecedented bubble. From the 8-0 bubble Suns to the fifth seed Heat making a run for the title, the NBA proved to us that anything was possible. Although some teams made some satisfying Cinderella runs, there also seemed to be several statistics that were either helped or harmed when players and teams entered the bubble. Some of the trends are easy to understand, but other trends tend to puzzle many fans, including myself.
The first statistic I wanted to look at was fouls per game by team. Since the noise was minimal in the bubble with only virtual fans, I would believe that more fouls would be called since the referees would be able to hear the slaps and collisions easier on layups and shots. Here is what I found:
On average, teams in the bubble averaged approximately 23 fouls per game, while teams outside the bubble averaged approximately 21 fouls per game. Like I hypothesized, I believe this discrepancy can be credited to the lack of fans in the bubble making it easier for referees to hear the slaps and contact when a player is shooting, or even when a player draws an offensive foul. A confounding factor to consider though, is that there was never really a team with “home team advantage” (unless you count the Orlando Magic!). Additionally, a lot of bubble games, like the Blazers and Grizzlies pre-play-in matchup, had severe playoff implications so those games may have been conducted with an abundance of intensity and may have skewed the foul statistics. The bubble sample size is pretty small compared to the NBA regular season, but still, there seemed to be a higher occurrence of fouls in the bubble than in the regular season.
After an extremely long NBA hiatus, I expected the quality of play to sharply decrease, especially when players like Jayson Tatum and Giannis Antetokounmpo were not able to practice for the majority of the hiatus. However, when comparing the turnovers per game and plus/minus between the regular season and the bubble, I was surprised. I picked these two statistics to analyze because I believe turnovers would accurately represent the sloppiness which teams play with and plus/minus would just be another interesting statistic to include. Although I would’ve expected the turnovers in the bubble to be much higher than during the regular season, the average for team turnovers in the bubble was only approximately one turnover higher than during the regular season (15.4409 and 14.5667, respectively). The plus/minus numbers when comparing the bubble and the regular season respectively were almost identical too: (-0.0045:-0.1667). What this indicates is that the quality of play in the bubble was almost identical to the regular season, meaning that even with a hiatus of over 100 days, NBA players consistently played at an elite level. While many believed that the quality of bubble games might have been quite low, these numbers suggest that NBA players played just as well in the bubble compared to the regular season, showing how much passion they have for the game.
The final metric that I wanted to analyze was three point shooting. I figured that the bubble would be a 3-point shooter’s paradise with minimal distractions. Again, the numbers here were surprising. While the averages for 3-pointers made and 3-point percentages between the bubble teams and all regular season teams were very similar, the top five teams were definitely able to improve their three point numbers. As you can see in the chart below, the top five teams in both categories improved their shooting percentages by a couple percentage points. One of the main reasons this occurred, as voiced from the players, was that their depth perception was improved since there were no fans sitting behind the backboard, and many players cited that this helped their shooting percentages. Additionally, as mentioned earlier, there was minimal crowd noise and distractions, so this also must have improved 3-point shooting in the bubble.
Adam Silver had an extremely unique idea with the creation of the NBA bubble, and as an Orlando native, I am really grateful that I was able to feel the aura of the bubble, as the bubble was only 10 minutes away from my home. As the NBA bubble era has now concluded, congrats to the Los Angeles Lakers, who knows what is in store. Although many fans were disappointed when the NBA season was postponed, I personally think that the bubble was the perfect idea to cap off this mysterious season.
*All statistics taken from NBA.com
Brian Li:
During the NBA’s time in the Orlando bubble, there were many who seemed to notice an uptick in three point shooting efficiency. With the performances of the likes of Jamal Murray, Donovan Mitchell, Jae Crowder, and others, it was easy to see why this theory came to mind. Objectively, many felt that catch and shoot along with open threes specifically seemed to be going in at a higher rate. Therefore, I wanted to test whether or not three point shooting percentages of different varieties in the bubble were significantly different from that of non-bubble play.
I decided to break down three point shooting into seven separate categories: overall, catch and shoot, pull ups, wide open, open, tight, and very tight. This could provide a snapshot of which specific types of three point attempts saw a significant difference in the bubble. Furthermore, I wanted to compare the three point attempts in the bubble with similar samples, since regular season shooting might be inherently different from playoff shooting. I decided to match up the 2020 bubble seeding games with the 2019-20 regular season games, and the 2020 bubble playoff games with the 2019 playoff games. I used a two-proportion z-test to compare any pair of samples, and the following were the results:
Based on these results, three point shooting for the most part was not significantly different during bubble play, at the 0.05 significance level. Almost every variety of three point shooting, both regular season and playoffs, did not increase significantly in efficiency in the bubble. However, there are some indications that catch and shoot efficiency was higher in the bubble. The difference between regular season and bubble seeding catch and shoot percentages barely missed the statistical cutoff, while playoff catch and shoot percentages saw a significant difference. Almost all other differences between bubble and non-bubble shooting were insignificant, most notably wide open and open three point attempts.
Despite my attempt to control for environment by separating regular season and playoffs and only comparing within these strata, there could be other confounding variables that affect the data. With respect to the regular season games, only 22 of the 30 teams played in the seeding games. Additionally, the 8 worst teams were weeded out, which may have artificially boosted three point shooting percentages in the bubble. The same issue occurs in the playoffs, as different teams made the playoffs between this season and last season, and many players were placed into different team contexts.
*All statistics taken from NBA.com