Wednesday, June 26, 2013

NBA Win Probability Added

One of the nice things about an in-game win probability model is that you can use it to see which plays (and players) had the biggest impact on the outcome of a game. Traditional box score stats, and even more advanced metrics like plus/minus, summarize player performance independent of the game situation. The box score counts Ray Allen's game-tying three pointer in game six of the Finals just the same as Mike Miller's three pointer made at 10:35 in the first quarter in the same game.

Everyone knows that Ray Allen's shot was much bigger than Mike's, even though they were worth the same amount of points. Win Probability Added is a stat that quantifies just how much bigger that play was. The basic idea is to score each play (and the player responsible) by looking at how that play changed the win probability for the team (see here and here for this concept applied to the NFL and MLB respectively).

Thursday, June 20, 2013

NBA Finals Game 7 - Win Probability Graph

Win probability graph for Game 7. Top play was Mario Chalmers' buzzer beating three pointer to end the third quarter. Lebron's pull up jumper with 0:27 on the clock will probably dominate the highlight reel, but it was the 24th most important play in terms of win probability. Tim Duncan's miss from point blank range had a much bigger impact on the game. More background here and here.

San Antonio Spurs88 Excitement5.7
Miami Heat95 Comeback0.8

Prior StatePlayEnd StateBeforeChangeAfter
Q3 | 0:05 | SAS:71 MIA:69 | Poss:MIAMario Chalmers makes 30-foot three point jumperQ3 | 0:00 | SAS:71 MIA:72 | Poss:SAS58.7%+10.3%69.0%
Q4 | 2:15 | SAS:85 MIA:90 | Poss:SASKawhi Leonard makes 25-foot three point jumper (Manu Ginobili assists)Q4 | 2:00 | SAS:88 MIA:90 | Poss:MIA93.3%-9.6%83.7%
Q4 | 11:45 | SAS:71 MIA:72 | Poss:MIAShane Battier makes 23-foot three point jumper (LeBron James assists)Q4 | 11:34 | SAS:71 MIA:75 | Poss:SAS70.5%+9.5%80.1%
Q4 | 1:34 | SAS:88 MIA:90 | Poss:SASLeBron James offensive reboundQ4 | 1:04 | SAS:88 MIA:90 | Poss:MIA78.3%+9.3%87.5%
Q4 | 0:47 | SAS:88 MIA:90 | Poss:SASTim Duncan misses hook shot (Chris Bosh defensive rebound)Q4 | 0:42 | SAS:88 MIA:90 | Poss:MIA80.6%+9.3%89.8%

Live Win Probability for Game 7 (maybe)

This will most likely crash and burn, but I will attempt to share the win probability graph realtime for tonight's deciding game 7. The graph will be in this post. I currently have game 6 data loaded as a placeholder. If everything goes according to plan, this will refresh with live data once the game starts tonight. But if it breaks, there is probably little chance I will be able to fix it.

Wednesday, June 19, 2013

The Biggest Comeback of the 2013 NBA Playoffs...

..was not Heat/Spurs in Game Six of the Finals.  That distinction belongs to the Chicago Bulls with their triple overtime victory over the Brooklyn Nets in game 4 of their opening round series (see table below).  With 2:59 left in the fourth quarter, the Bulls were down by 14 points and had a win probability of 0.2%.  The Bulls ended the game on a 16-2 run and prevailed (eventually) in overtime.  At their lowest point, the Heat's win probability in game six last night was 1.5%.

The Heat's comeback wasn't even the second biggest of the playoffs.  In game 1 of the Spurs-Warriors round 2 series, the Spurs were down by sixteen with 4:18 left to go in the game, working out to a win probability of 0.4%.  An 18-2 run by the Spurs sent the game to overtime, and then double overtime, and then this.

Tuesday, June 18, 2013

NBA Finals Game 6 - Win Probability Graph

Here is the win probability graph for Game 6. Ho hum. If Ray Allen doesn't knock down that three to force overtime, the "top" play of the game is Lebron's turnover with 0:39 left.

The comeback factor of 66 in this game means that, at the Heat's nadir (down by 4, Spurs ball, 0:28 on the clock), their odds of winning the game were 66 to 1. More background here and here.

San Antonio Spurs100 Excitement8.9
Miami Heat103 Comeback66

Prior StatePlayEnd StateBeforeChangeAfter
Q4 | 0:06 | SAS:95 MIA:92 | Poss:MIARay Allen makes 25-foot three point jumper (Chris Bosh assists)Q4 | 0:05 | SAS:95 MIA:95 | Poss:SAS6.1%+39.8%45.9%
Q4 | 0:58 | SAS:91 MIA:89 | Poss:MIALeBron James lost ball turnover (Kawhi Leonard steals)Q4 | 0:39 | SAS:91 MIA:89 | Poss:SAS36.8%-19.4%17.4%
Q5 | 0:08 | SAS:100 MIA:101 | Poss:SASManu Ginobili lost ball turnover (Ray Allen steals)Q5 | 0:02 | SAS:100 MIA:101 | Poss:MIA73.3%+18.8%92.1%
Q4 | 1:07 | SAS:89 MIA:89 | Poss:SASTony Parker makes 12-foot two point shotQ4 | 0:58 | SAS:91 MIA:89 | Poss:MIA55.1%-18.3%36.8%
Q4 | 0:05 | SAS:95 MIA:95 | Poss:SASEnd of 4th QuarterQ5 | 12:00 | SAS:95 MIA:95 | Poss:45.9%+17.8%63.7%