Methodological Reviews of Basketball Models – Part 4 – WARP

Introduction

Welcome to the fourth post in this series! In the first one, I introduced my plan for conducting methodological reviews of basketball statistical models. In the second, I reviewed the Wins Produced model. Then, in the last post, I took a look at Win Shares. Today, I will analyze the Wins Above Replacement Player (WARP) model developed by Kevin Pelton.

The Basics of WARP

As Pelton outlines at the beginning of his write-up on WARP, he based much of his work on Dr. Dean Oliver’s. Since I already wrote about Dr. Oliver’s model, I will try not to delve too much into the parts of his writing used by Pelton. Doing so would make this series too repetitive to be ideal as a review.

My opinion is that there are two pivotal frameworks in use by Pelton: Dr. Oliver’s work is the first, while the second is related to his use of the concept of a “replacement player”. Having previously described Oliver’s impact on modern basketball analytics, let’s focus on the effect of the latter framework.

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Methodological Reviews of Basketball Models – Part 3

Introduction

In the first post of this series, I introduced my plan for conducting methodological reviews of major basketball statistical models. In the second installment, I looked at the Wins Produced model. In keeping with the theme of “Wins-named” metrics, we turn to Win Shares.

Win Shares is a basketball adaptation of Bill James’ work with baseball statistics spanning decades. Justin Kubatko adapted James’ methodology to basketball. Kubatko’s explanation shows how to calculate the number of Win Shares for a player, so my review will rely on his exposition.

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Hey Siri, will the Rockets make the playoffs this year?

By Alan Moghaddam

I’ve been obsessed with Machine Learning lately. Like really obsessed. The problem is that I do not care about predicting how many passengers would have survived the Titanic sinking, or if a computer can tell whether an image is a dog or cat (all cats or you need not apply), or performing handwriting analysis to see if someone drew a 0 or a 6. Fret no more, I’ve done it – I have made a machine learning algorithm that scrapes data from basketballreference.com and can predict who will and will not make the playoffs!

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Methodological Reviews of Basketball Models – Part 2

by Andre Vizzoni

Introduction

As outlined in the first post of this series, I will be reviewing several models, beginning with Wins Produced. The creators of Wins Produced are David Berri, Martin Schmidt, and Stacey Brook, three sports economists. Their work on the subject of basketball analysis spans many academic papers, specially Berri’s work, and has also spawned two books and two blogs.

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Methodological Review of Basketball Models – Part 1

by André Vizzoni

Introduction

The series beginning here will be my first foray into topics beyond my model for predicting sports results. Specifically, I plan to undertake a methodological review of a few well-known basketball models which have been influential in the analytics community. The review will examine the “how” and “why” of those models, and may level criticism at parts of them. As there are a number of subjects that must be broached prior to the review proper, this introductory post will be shorter than its successors.

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Robert Covington’s Seamless Adaptation to the Houston Rockets’ Defensive Scheme

After the Houston Rockets pulled off the deal for Robert Covington at this year’s trade deadline many wondered what the Rockets were doing. How would their team look, especially on the defensive end? In some respects, the Rockets performed as well after the trade as before, and one of the biggest factors in their defense has been the newest factor: Robert Covington.

Where did Covington come from? How did he land here, as a highly-prized trade target First, let’s go back to the beginning of Robert Covington’s career.

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A Prediction Model for Sports Match Results – Part 4

Introduction

The first three parts of this series of articles were focused on a static model for predicting match results. With that model, our measures of team quality (offensive quality, defensive quality, and home field advantage) were static, meaning that they were not allowed to change as time progresses. In other words, a team was considered as having the same quality whether you were trying to predict the team’s results in week 1 or its results in the last week of the season.

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Why Don’t We Care About NBA-All Star Weekend?

There is something fundamentally wrong with the NBA All-Star game and All-Star Weekend at large. The new NBA Jam-like rule change, while interesting, does not fix what plagues the NBA’s premier regular season event.

So What Is the Problem?

Give the NBA credit, they have shoehorned the All-Star event into the perfect time period. Those feeling hungover from the Super Bowl have something to watch, and those who are waiting for prime time NCAA basketball to come during March have an event to hold themselves together in the meantime. If you are an NBA fan, chances are you were already going to watch the All-Star activities. By picking mid-February, the league has found a period in the sports calendar where the NBA has center stage.

In spite of the logistical victory, fans do not care and players do not care. The NBA has seen a sharp decline in viewership numbers for the All-Star game from the ’90s leading into the 2000s, and then almost no growth since 2005 (Please note the Lockout of 1999 had the All-Star Game cancelled, all data from https://en.wikipedia.org/wiki/National_Basketball_Association_on_television). Viewership is not the best metric for fan engagement, but it does give a decent look at where fans stand with respect to watching the actual game (admittedly, it does not measure interest in the other festivities during All-Star Weekend). I also examined the voter numbers to assess engagement, but worried that the results might be unreliable. Due the constant changes in how and where fans could vote, any correlations might not be instructive.

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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.

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A Prediction Model for Sports Match Results

by André Vizzoni

Introduction

In this post, I will introduce a prediction model that was the product of a research project that spanned four years (winning a few awards) and was the final project for my degree in Statistics. For those interested in the final project, here it is – though I warn everyone in advance that it is in Portuguese. The objective of this post, then, is to translate the most central parts of that project to English while, at the same time, talking about applications of the model to basketball data, since the original project used soccer data.

First, I will give an intuitive explanation of the model, with no equations or mathematical concepts introduced. Next will come the methodology section, where there will be a lot more maths and formal definitions. As such, people who are interested only on the intuitive definitions might wish to skip the methodology section). The idea behind this structuring of the post is for it to be understandable, both by laypeople and by people well versed in statistics. Finally, in the discussion section there will be a few summary comments, as well as a preview of things to come on this site.

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