Math and Basketball

Math & Basketball: Astronomy used to be just watching pretty stars, too BASKETBALL ON PAPER Dean Oliver Author, Basketball on Paper Consultant to the Seattle Supersonics Using Sports to Teach Math Symposium Seattle, WA May 13, 2006 1 Some History  Every science we have today was once just “interesting”      Chemistry Biology Astronomy Finance and economics Physics   Interesting + math = science Math = Science - Interesting Dean Oliver deano@rawbw.com BASKETBALL ON PAPER 2 Language and logic first…  Score a game 5 CHI UTA 6 CHI UTA 8 CHI UTA 8 CHI UTA 8 CHI UTA 23D/ 91- A 32R 12D/ 3 32 12D 14- X 13R 9D/ 33 23 33 13F32(1)X* 12D/ 14 32 3- R 00R 12D 32++B 33D/ 91 23D 33 23++A 12D/ 32++2 33 / 9D 23D- 3 13R- L 13F12(1) 23 91 33 9 23D- B 14R 32D 12D/ 3 32DF91(1)X* 33D/ 23D 9 33 23 13 9-Y 3RD / 12 14 32 12++R 4 6 8 9 11 BASKETBALL ON PAPER Dean Oliver deano@rawbw.com 3 …Then counting…      How many lines? How many lines with a score? How many touches? How many post-ups? How many offensive rebounds off missed free throws? BASKETBALL ON PAPER Dean Oliver deano@rawbw.com 4 …And Analysis  Same number of possessions…   Equivalence scale on possessions Per available rebound Points per possession Four Factors     Basketball on Paper    Effective shooting percentage Turnovers per possession Offensive rebounding percentage Free throw rate Dean Oliver deano@rawbw.com BASKETBALL ON PAPER 5 Stories to tell  Grades    Is ___ the next Michael Jordan? Who should we draft? Is __ a good coach? Why so many offensive rebounds? Is offense better when forcing more touches? Should we double team the post? Is it easier to shoot an open jump shot from 3pt range or a contested one from 2pt range? Should a team pay more to win? When do players get their big paycheck?  Tactics      Financial   BASKETBALL ON PAPER Dean Oliver deano@rawbw.com 6 The Possession Framework    Possessions are equal What you do per possession is what matters Possession ends:     Missed shot rebounded by defense Made field goal, no free throw Turnover Made last free throw  Possession formula:  (FGA – FGM – OR) + FGM + TOV + 0.4*FTA Dean Oliver deano@rawbw.com BASKETBALL ON PAPER 7 Floor% and Play%  Floor%: Percentage of possessions on which there is a score  Scoring Possessions/Possessions  Play%: Percentage of “plays” on which there is a score  Scoring Possessions/Plays BASKETBALL ON PAPER Dean Oliver deano@rawbw.com 8 Four Factors  Effective Field Goal Percentage  (FGM + 0.5 * FG3M)/FGA  Turnover Percentage  TOV/Poss OR/(OR + OppDR) FTM/FGA Dean Oliver deano@rawbw.com  Offensive Rebounding Percentage   Free Throw Ratio  BASKETBALL ON PAPER 9 Test!  Seattle 1998    eFG%: 52.1% FT%: 72% TOV%: 15.7% eFG%: 51.9% FT%: 68% TOV%: 16.2% Dean Oliver deano@rawbw.com  LA Lakers 1998     Better offense? 10 BASKETBALL ON PAPER Answers  Lakers had better offense  111.9 pts/100 poss to 111.4 Shot worse from everywhere Rebounded worse Turned ball over more Shot 600 more free throws! More shots of overall higher percentage shot Dean Oliver deano@rawbw.com  How?     But…   BASKETBALL ON PAPER 11 More Framework: Estimating Wins   Wins come from point difference (points/possession) Wins ~    A*(points – points allowed) + 0.5 B*(pts/poss – pts allowed/poss) + 0.5 pointsC/(pointsC + points allowedC) BASKETBALL ON PAPER Dean Oliver deano@rawbw.com 12 Wins from a Bell Curve Figure 2: Distributions of Home and Road Scores, 2000-2001 and 2001-2002 Seasons 20% 18% Percentage of Games 16% 14% 12% 10% 8% 6% 4% 2% 0% Road Scores Home Scores 60 61 -6 5 66 -7 0 71 -7 5 76 -8 0 81 -8 5 86 -9 0 91 -9 96 5 -1 10 00 11 10 05 61 11 10 11 11 15 61 12 20 11 12 25 613 0 >1 30 Score <= BASKETBALL ON PAPER Dean Oliver deano@rawbw.com 14 Bell Curve Principles     Consistency matters Playing up or down to opponent matters Don’t blow teams out by too much Unbiased referees change odds BASKETBALL ON PAPER Dean Oliver deano@rawbw.com 15 Player Evaluation  What makes a good player?  Almost the same as what makes a good team Roles/Interactions affect everything     Volume of shots Communication Coordination BASKETBALL ON PAPER Dean Oliver deano@rawbw.com 16 Decreasing Marginal Returns Player Skill Curve (Averaged) 45% 40% 35% 30% % Tm Poss 25% 20% 15% 10% 5% 0% 75 85 95 105 Rating 115 125 135 J. Stackhouse A. Iverson M. Jordan BASKETBALL ON PAPER Dean Oliver deano@rawbw.com 17 Optimize Lakers’ Offense Unbalanced offense Player Bryant Odom Parker Brown Walton Totals % Tm Poss Off. Rtg. 36% 114 19% 111 15% 107 14% 106 16% 101 100% 109 More balanced offense Player Bryant Odom Parker Brown Walton Totals % Tm Poss Off. Rtg. 26% 119 22% 103 18% 99 16% 98 18% 95 100% 104 BASKETBALL ON PAPER Dean Oliver deano@rawbw.com 18 Overall Player Ratings    “Ratings” aren’t objective What are you measuring? Offense, defense, (in)tangibles BASKETBALL ON PAPER Dean Oliver deano@rawbw.com 19 Other Projects       Best player to step up to help offense What to emphasize on defense How will players develop? How to help them? What tactics to take against good teams? What tendencies do teams have to take advantage of? How to predict player performance from another league? Dean Oliver deano@rawbw.com BASKETBALL ON PAPER 20 Work with 82games.com  They do research projects     Ahead by 3, foul or defend? Does Steve Nash help his teammates? What does Kobe Bryant do in the clutch? How likely is it to make a shot after making the previous one? BASKETBALL ON PAPER Dean Oliver deano@rawbw.com 21