Predicting Game 5 of the NBA Finals Using Log5 Method


To give a statistical perspective on Game 5 of the NBA Finals, I ran a basic log5 prediction.  The log5 method gives the percent chance of a team winning by comparing the team and its opponent’s Pythagorean win percentage, the winning percentage derived by comparing a teams points scored and allowed, rather than wins and losses.

Jun 9, 2013; Miami, FL, USA; Miami Heat small forward LeBron James (6) shoots the ball over San Antonio Spurs center Tiago Splitter (22) in the third quarter during game two of the 2013 NBA Finals at the American Airlines Arena. Mandatory Credit: Robert Mayer-USA TODAY Sports

First, I calculated Miami’s chance of winning based on the two teams regular season performance.  Miami allowed 103.7 points per 100 possessions and scored 112.3, while San Antonio allowed 101.6 and scored 108.3.  This gives Miami a Pythagorean win percentage of 78.83 percent, and San Antonio one of 74.15 percent.

When A= Pythagorean win percentage of team A and B=Pythagorean win percentage of team B, team A’s chance of beating team B is:

 (A – A * B) / (A + B – 2*A*B)


Using this formula and regular season performance, Miami has a 56.49 percent chance of winning Game 5.  To calculate a predicted score, each teams percent production of the league average offensive and defensive rating is calculated.  Miami produced 106.137 percent of the average offensive rating and allowed 97.923 percent of the average offensive rating to opponents.  San Antonio scored 102.227 percent of the league average offensive rating and allowed 95.93 percent of the league average.

In a game against San Antonio, Miami’s expected output is their percent of the league average offensive production times the percent of the league average offensive production allowed by San Antonio times the league average offensive production.  Using this method, Miami is expected to score about 108 points in 100 possessions versus San Antonio, while San Antonio is expected to score 106.5.  The average pace for the 2012-13 playoffs is 89.5 possessions per game.  Adjusting for the average pace, Miami is expected to beat San Antonio 97-95.

This projection was repeated using each team’s performance in the Finals.  Miami has scored 106.6 points per 100 possessions and allowed 104.9.  In the most surprising of coincidences, San Antonio has scored 104.9 and allowed 106.6.  Using these numbers, Miami has a 62.95 percent chance of winning, and the expected score is 97-94.

While I would hesitate to bet my life’s savings on these predictions, this does give a reasonable expectation for will be a very interesting game.