The Pennsylvania State University Schreyer Honors College
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THE PENNSYLVANIA STATE UNIVERSITY SCHREYER HONORS COLLEGE DEPARTMENT OF STATISTICS ANALYZING AND PREDICTING THE SUCCESS OF NBA SECOND-ROUND PICKS USING ADVANCED COLLEGE PERFORMANCE METRICS JAY YANG SPRING 2019 A thesis submitted in partial fulfillment of the requirements for a baccalaureate degree in Statistics with honors in Statistics Reviewed and approved* by the following: Andrew Wiesner Associate Teaching Professor of Statistics Thesis Supervisor Matthew Beckman Assistant Research Professor of Statistics Honors Adviser * Signatures are on file in the Schreyer Honors College. i ABSTRACT The second-round is often an overlooked portion of the NBA draft, and second-round draft picks are often viewed as peripheral assets in trades. However, finding key contributors in the second-round can go a long way towards building a successful team. This thesis aims to identify key statistics from a player’s college career that may be able to help predict a player’s success in the NBA. To do so, various methods of regression will be used with a variety of advanced college basketball statistics as potential predictor variables to produce models for both longevity and productivity in the NBA. In addition, these models will be applied to previous second-round picks to see how well they predict the performance of well-known NBA second- rounders. In producing these models, win shares, and more specifically, defensive win shares, were found to be a significant predictor for multiple responses, providing evidence that defensive win shares in college may be a crucial advanced statistic to key in when searching for value in the second-round of the NBA draft. In addition, the success of forwards also seemed to differ from the success of non-forwards. When applied to past second-round picks, these models predicted favorable outcomes for notable NBA second-round picks, such as Hassan Whiteside and Draymond Green. ii TABLE OF CONTENTS LIST OF FIGURES ..................................................................................................... iv LIST OF TABLES ....................................................................................................... v ACKNOWLEDGEMENTS ......................................................................................... vii Chapter 1 Introduction ................................................................................................. 1 History of Second-Round Draft Picks .................................................................. 1 History of Analytics in Basketball ........................................................................ 4 Overview of Advanced Statistics Used in Basketball .......................................... 6 (Offensive and Defensive) Win Shares ......................................................... 7 Player Efficiency Rating (PER) ..................................................................... 8 True Shooting Percentage.............................................................................. 9 Effective Field Goal Percentage .................................................................... 10 (Offensive and Defensive) Rebounding Percentage ...................................... 10 Assist Percentage ........................................................................................... 10 Steal Percentage/Block Percentage ............................................................... 11 Turnover Percentage ...................................................................................... 11 Points Produced ............................................................................................. 12 Offensive and Defensive Rating .................................................................... 12 (Offensive and Defensive) Box Plus/Minus (BPM) ...................................... 13 Previous Work Done Predicting NBA Draft Pick Success .................................. 15 Using College Statistics to Predict NBA Outcomes ............................................. 16 Chapter 2 Methods ....................................................................................................... 18 Data Collection ..................................................................................................... 18 Regression Modeling Types ................................................................................. 22 Poisson Regression ........................................................................................ 23 Multiple Linear Regression ........................................................................... 23 Logistic Regression ....................................................................................... 24 Model Selection .................................................................................................... 25 Stepwise Regression ...................................................................................... 25 k-fold Cross-Validation ................................................................................. 26 Mean Absolute Error (MAE)......................................................................... 26 Chapter 3 Data Analysis and Results ........................................................................... 27 Correlation ............................................................................................................ 27 Developing Regression Models to Predict NBA Outcomes ................................. 31 Years Played .................................................................................................. 31 Win Shares..................................................................................................... 35 Win Shares Per 48 ......................................................................................... 39 iii Vesting ........................................................................................................... 43 Application to Recent Second-Round Picks ......................................................... 47 Chapter 4 Conclusions ................................................................................................. 51 Review .................................................................................................................. 51 Previewing the 2019 NBA Draft .......................................................................... 53 Limitations ............................................................................................................ 54 International Players ...................................................................................... 55 High School Players ...................................................................................... 56 Future Directions .................................................................................................. 56 Appendix A Model Output and Residual Plots........................................................... 58 BIBLIOGRAPHY ........................................................................................................ 61 iv LIST OF FIGURES Figure 1: Draft Position vs. Average Win Shares for NBA Draft Picks Between 2003- 2012 (Brahme 2017) ............................................................................................. 2 Figure 2: Oakland Athletics’ Wins vs. Payroll Expectation with Beane as General Manager (Morris 2014) ......................................................................................... 6 Figure 3: Correlation Coefficients and Significance for All Players ........................... 28 Figure 4: Correlation Coefficients and Significance for Guards (n=154) ................... 28 Figure 5: Correlation Coefficients and Significance for Forwards (n=158) ................ 29 Figure 6: Correlation Coefficients and Significance for Centers (n=44) ..................... 30 Figure 7: Histogram for Number of Years Played in the NBA by Second-Round Picks 31 v LIST OF TABLES Table 1: Result of Final Box Plus/Minus Regression Model with Coefficients (“Basketball Reference” 2019) ............................................................................. 14 Table 2: List of Statistics Used .................................................................................... 19 Table 3: Backgrounds of Second-Round Picks from 1996-2018 ................................ 20 Table 4: Availability of Statistics Used by Year ......................................................... 21 Table 5: Summary Statistics for Second-Round Picks from 1996-2015 ..................... 27 Table 6: Results of 10-fold Cross-Validation for Years Played .................................. 32 Table 7: Coefficients for Final Regression Model for Years Played ........................... 32 Table 8: Top 10 Players for Predicted Years Played ................................................... 33 Table 9: Predicted Years Played for Notable NBA Players ........................................ 34 Table 10: Results of 10-fold Cross-Validation for Win Shares ................................... 35 Table 11 : Coefficients for Final Regression Model for Win Shares .......................... 36 Table 12: Top 10 Players for Predicted Win Shares .................................................... 38 Table 13: Predicted Win Shares for Notable NBA Players ......................................... 38 Table 14: Results of 10-fold Cross-Validation for Win Shares Per 48........................ 39 Table 15: Coefficients for Final Regression Model for Win Shares Per 48 ...............