Drip

Featured

Matchup-Based Defense

 

Defense is the unsolvable puzzle in NBA analytics. No matter how advanced the advanced stats get, defensive metrics continue to crash against the same conundrums. Better data often leads to better models, and recent years have seen a dramatic improvement in the quality of defensive data available for analysis. Tracking data, opponent shooting data, play-by-play data, and more have all played a hand in modern defensive analysis. In spite of the improvements, or perhaps in part because of the improvements, it is clear that defensive analysis is still not highly accurate.

Most defensive metrics which are currently extant are based on one of two schools of thought. In order to take stock of why defensive analysis is still frequently inaccurate, it will help to investigate the underlying assumptions behind most current models.

The Plus/Minus School of Thought

The most popular method by far is The Plus/Minus School, which counts BPM, RPM, RAPM, PIPM, and more among its adherents. The distinguishing precept of the Plus/Minus School is the belief that we can ascertain a player’s defensive value by evaluating the team’s performance with him on the court, if only we properly adjust for strength of opponent, the team’s talent level, the team’s performance with the player off the court, and the player’s performance level in seasons past. The adjustments made to raw plus/minus are attempts to extract reliable data by excising confounding variables.

Continue reading “Matchup-Based Defense”

Beyond the Box Score

 

It is time to stop evaluating players based on statistical feats. The ubiquity of statistical data has brought with it a ready supply of historical comparisons. In today’s NBA, one can hardly turn around without running into a stat trumpeting a player as “the first player since MJ to have 18 consecutive games of 20-5-5”. Who can ignore the box score aggregators, with their perpetual lists of “top performances of the night” that are oriented mainly around points, rebounds, and assists? The basketball community is awash in counting stats-based evaluations, but it’s time to cut it out.

The comeuppance has been a long time coming, to be perfectly honest. Fans have long prized points, rebounds, and assists as basketball’s version of the “Triple Crown” – a trio of statistics that can combine to depict a player’s value. Such an outcome is to be expected, since those three statistics are usually the largest numbers in any box score; our eyes are drawn to big numbers. In The Book of Basketball, Bill Simmons concretized the method of measuring players by Points+Rebounds+Assists in constructing his all-time rankings, which certainly did nothing to cool the ardor of counting stat acolytes.

It Was Never a Good Idea

Adding together counting stats was a bad idea to begin with. Taking values that describe discrete events and adding them without modification is among the poorest methods of measuring a player’s impact. Every box score statistic (every statistic period, as a matter of fact) exists on a certain scale. While it is quite common for a player to score 10 points in a game, and somewhat common for a player to grab 10 rebounds in a game, it is decidedly uncommon for a player to register 10 steals in a game. The scale – or range of normal values – for steals is much smaller than the scale for points. Since points, rebounds, and assists each have their own scale, adding them is always going to privilege points above the other components.

Continue reading “Beyond the Box Score”

A Prediction Model for Sports Match Results – Part 3

 

by André Vizzoni

Introduction

Parts one and two of this series of posts were quite heavy with probabilistic jargon (even with me trying to lighten it), and I hope this third one won’t be like that. The main objective of this article is to show the readers how the outputs of this model fit within the current basketball analytics framework. With that in mind, I will be looking at the relationship between the parameters of every team and the following stats:

  • Team 2-Point Field Goal Percentage (T2FG%)
  • Opponent 2-Point Field Goal Percentage (O2FG%)
  • Team 3-Point Field Goal Percentage (T3FG%)
  • Opponent 3-Point Field Goal Percentage (O3FG%)
  • Team Effective Field Goal Percentage (TEFG%)
  • Opponent Effective Field Goal Percentage (OEFG%)
  • Team True Shooting Percentage (TTS%)
  • Opponent True Shooting Percentage (OTS%)
  • Team Offensive Rebounding Percentage (TOREB%)
  • Opponent Offensive Rebounding Percentage (OOREB%)
  • Team Defensive Rebounding Percentage (TDREB%)
  • Opponent Defensive Rebounding Percentage (ODREB%)
  • Team Free Throw Rate (TFT%)
  • Opponent Free Throw Rate (OFT%)
  • Team Turnover Percentage (TTO%)
  • Opponent Turnover Percentage (OTO%)

Since I’m using this Justin Jacobs’ article as a guide, it also makes sense to look at the Four Factors Adjusted Ratings, hosted on this website. First, I will lay out the Methodology for my analysis. Next, I will analyze the scatter plots of the model parameters versus the assorted stats in the Analysis section. On the basis of those results, I will use the Discussion section to make sense of all that the analysis unearths.

Continue reading “A Prediction Model for Sports Match Results – Part 3”

Can You Give Me Some Stats to Prove that Russell Westbrook Steals Rebounds?

 

          Properly valuing and evaluating rebounds has become something of a hot topic in recent years with Russell Westbrook averaging a triple double for three consecutive seasons despite being one of the smallest players in the history of the league to average 10 rebounds per game. Much of the discussion about his incredible feat has centered on whether or not it is the case that Westbrook’s rebounding numbers are inflated due to Westbrook taking a disproportionate amount of defensive rebounds which could be collected by other members of his team.

          Naturally, a lot of people are looking for stats to support the conclusion which they’ve already reached (thus the tongue-in-cheek title). I think we can analyze this question, within the context of a useful estimation of rebounding value for the entire league.

Continue reading “Can You Give Me Some Stats to Prove that Russell Westbrook Steals Rebounds?”

The Factors That Influence NBA Home Court Advantage

 

by Dashiell Nusbaum

Alternate link to story: https://medium.com/push-the-pace/the-factors-that-influence-nba-home-court-advantage-2a5a602f8c1f

Many see sports as the ultimate “equal playing field” — where the same rules, regulations, and opportunities exist for all, where the best team will emerge victorious. This isn’t always the case.

We find the existence of a “home court advantage” across sports, where teams are more likely to win at home than away. This is especially true of the NBA, which has the largest home team advantage among the four major American sports. The existence and magnitude of a home court advantage has been extensively studied; however, we lack an understanding of the factors that cause certain teams to have larger home court advantage than others.

I found the average regular-season home court advantage for all 30 NBA teams from 2008-09 through 2018-19. Home court advantage is a team’s winning percentage at home minus their winning percentage on the road. For example, from the 08-09 through 18-19 season, the Denver Nuggets won 75.62% of their home games and 46.52% of their away games. Therefore, Denver’s home court advantage = 75.62% – 46.52% = 29.10%.

Continue reading “The Factors That Influence NBA Home Court Advantage”

Applied Efficiency: A New NBA Scoring Efficiency Stat

 

by Baltej Parmar

Comparing players is the stock in trade of fandom. Whatever your team, everyone wants to know which player is better than his peers. Statistics allow us to compare various aspects of player performance – perhaps most notably efficiency. “Russell Westbrook has a career FG% of .434, while Stephen Curry has a FG% of .476. The difference isn’t much.” Are we sure that a difference of .042 is not much, though? The scale of statistics can make it difficult to use them responsibly in comparisons. In the example above, Curry makes 42 shots more than Westbrook out of 1,000. Since a player doesn’t take 1,000 shots in a game, it is not directly obvious how much more likely Curry’s team is to win a game based on the difference in FG%. What if we had a better way to measure how much a player’s shooting impacts the score on a game-by-game basis? That’s why I’m introducing Applied Efficiency, a new NBA stat which does just that.

Continue reading “Applied Efficiency: A New NBA Scoring Efficiency Stat”

Who is Really the Best Defensive Center in the League?

 

As with the previous posts in this series which detailed the best defenders at each position, I start with the question “Who are the best defensive centers in the league?” In order to address the question properly when evaluating centers, however, it is necessary to answer a prior question. What is a center’s defensive role in the modern NBA? During some prior eras, the center could remain near the basket either defending a fellow behemoth on the low block or walling off the path of opposing drives. Rule changes constricted the scope of zone defense. Then, the 3-point shooting revolution caught even big men in its tantalizing web. For the first time in basketball history, forces conspired to pull centers away from the basket for good.

Photo by Rick Bowmer, AP

As always happens in games of strategy, however, there were side-effects to stylistic changes. The spacing afforded by stretch bigs has meant that dribble penetration continues to be an integral part of every team’s offensive attack. Having fewer big bodies in the way makes driving easier. As a result, the role of “rim protector” is still very much alive. Teams in today’s NBA still need interior defense from their center.

At the same time, teams also need their center to be able to cover quicker opponents on the perimeter. The center’s role now lies somewhere in between the inside and the outside. When we ask who the best defensive centers are, we are really asking two things: 1) Who is the best rim protector? 2) Who is the best at defending on the perimeter?

Continue reading “Who is Really the Best Defensive Center in the League?”

Failure to Launch

 

by Alan Moghaddam

The Houston Rockets are at a point of critical failure – or rather, they have reached a crux with more than one point of critical failure.

The Rockets’ record stands at 13-7 roughly a quarter of the way into the regular season. It has finally been long enough to shake off the “it’s too early to comment” crowd, and we can finally make some valid statement about this team long-term. To all appearances, things are not looking particularly spectacular for a team that entered the season with championship expectations.

Continue reading “Failure to Launch”

What is TPA?

 

by Alan Moghaddam

Chances are if you’re into sports you’ve seen the famed charts from @NBA_Math that feature overlapping pictures of NBA players in a conventional Cartesian plot with a line plotted on it (y=-x). Anything above the line is good, anything below is bad, and average values will tend to walk the line. The graph is a visual attempt to quantify some mystery statistic known as TPA.

This is a standard TPA graph from @NBA_Math

What is TPA?

This is something of a loaded question; the acronym TPA stands for “Total Points Added”. The basic idea behind it is that a player adds points on offense and defense. You then total these subsections to get TPA.

Unfortuantely, the definition above is rather incomplete. We now need to understand Offensive Points Added (OPA) and Defensive Points Saved (DPS), the components which make up TPA. The two subcategories are much more complex than TPA alone.

To get OPA and DPS, we need to use “Box Plus/Minus,” an all-in-one statistic created by Daniel Myers and hosted at basketball-reference.com. I promise we are almost at the bottom of the well here in terms of stat definitions. Box Plus/Minus is a relativistic stat that gauges a player’s impact on team performance when s/he is on the court. S/he again will have an impact on both defense and offense, so accordingly Box Plus/Minus can break down into two stats: Offensive Box Plus/Minus (OPBM) and Defensive Box Plus/Minus (DPBM). We can already see that TPA has the same structure as Box Plus Minus; both purport to measure a player’s impact on both ends of the floor. What is the difference between the two?

Equation 1. Calculation of TPA as a function of Defensive Points Saved and Offensive Points Awarded
Continue reading “What is TPA?”

A Prediction Model for Sports Match Results – Part 2

 

Introduction

As outlined in the first post, this installment of the series will be about the model’s estimates and predictions. I will also touch on how to compare predictions between models. For all that to work, I will have to introduce a few mathematical definitions. In a similar way to the first post, I will give both an intuitive explanation of every concept and a mathematical explanation.


The Estimates section will begin with an explanation of how the model fits the data (with a few graphs to show the process of finding the estimates for last season’s NBA), followed by a brief introduction on Bayesian inference. Next, the Model Comparisons section will define the predictive likelihood of a model, and how to calculate it. I will also discuss a few different ways to compare predictions. Finally, in the Discussion section, I will offer critiques of the work presented in this post.

Continue reading “A Prediction Model for Sports Match Results – Part 2”

The Best Defensive Power Forwards in the NBA

 

Small ball is no longer the wave of the future – it’s the wave of the present. The 80’s and 90’s featured brawny, bruising power forwards who could soak up punishment in the post, clean the glass, and protect the paint as weak side shot blockers. In a game dominated by giants, power forwards were the centers’ sidekicks. Even the beginning of the 21st century saw the San Antonio Spurs’ “Twin Towers” follow the same frontcourt structure that had held sway throughout the league’s existence.

AP Photo/Eric Gay

Change, though, is persistent. Stylistic and strategic changes alter the face of the league regularly. In the last decade, those changes have eroded the physical profile of the standard power forward. Horace Grant has given way to Jerami Grant. As stretch 4’s have gradually replaced the 4’s of yesteryear, the function of power forwards on the defensive end has changed considerably. As with all changes related to lineup construction, the small ball revolution is an arms race. The more stretch 4’s there are who can shoot from outside, the more teams need their “power forwards” to defend on the perimeter. Today’s power forward must be able to stay in front of some opponents outside while still holding his own inside.

Continue reading “The Best Defensive Power Forwards in the NBA”