Strength of Schedule Comparison
It is just the third week of 2016-17 NBA season, yet there are enough data to compare teams’ performances. Winning share is one of the key stat to look how successful a team is, but as each team plays different teams with a different time, that can also be misleading in the beginning of a season. Thus, using the Ratings Percentage Index (RPI) and Strength of Schedule is better.
RPI (ratings percentage index) is a rating that applies to a team’s record and schedule such that the stronger the opponents, the higher the RPI rating. It is calculated as the sum of ¼ of team win record, plus ½ of its opponents’ records plus ¼ of opponents’ of opponents’ records. But since home games and road games aren’t equal in terms of difficulty, we calculated a weighted win record by taking 0.75 for a home win and 1.25 for a road win. Similarly 0.75 for road loss and 1.25 for home loss.
Additionally, we also calculated strength of schedule (SOS) which refers to the difficulty or ease of a team’s opponent as compared to other teams. It is the stat showing how the past games of a team are easy compared to other teams’ past games. There are various approaches to calculate SOS but we used the classical method with a slight modification, which is adding opponents’ record and opponents’ opponents’ record but regarding the game location. So we took the average of overall win-loss ratio and home/road win-loss ratio of teams according where the games are played. It is more complicated but more reasonable.
The following tables summarizes the result. Despite 3 losses, Houston Rockets have the highest RPI thanks to 4 winning road games, including 1 at San Antonio. Los Angeles Clippers have second best RPI as they won 7 of their first 8 games. On the other hand, New Orleans Pelicans is at the bottom with the smallest RPI as they began to the season very badly. As for SOS, Dallas Mavericks have the toughest schedule until now with 0.605.
For the remaining games, we also examined teams’ schedules. We not only counted their rest days before each game and types of B2B games, we also calculated the Strength of Schedule for rest of the season for all teams. While doing it, we took into account the home/road factor and we gave different difficulty coefficients (for instance 1 for 3+ rested games, 1.35 for Road to Road type of B2B game etc.) according to rest days. We finally multiplied them with the opponents’ winning percentages of each game on the schedule and took the averages. The following table shows this analysis result. Minnesota Timberwolves have the hardest remaining schedule and Houston Rockets have the relatively easiest.