Adjusted Win Percentage: Where Does Your Team Stand?

We are now roughly a quarter of the way into the 2013-2014 NBA season.  So, how is your favorite team stacking up against the rest of the league?  Who might be this year’s Cinderella story?  Are the Pacers really the best team in the league?

An obvious way that many fans to try to answer these questions is by simply looking at league standings, sorted by win percentage.  Though this would be directionally informative, one clear problem with this approach is that all wins are treated equally.  For instance, the Dallas Mavericks’ recent win against the surging Portland Trail Blazers would be treated the same as their win against the struggling Milwaukee Bucks.  With each team playing only roughly 20 games thus far, not all schedules have been comparable.  Some teams, take the San Antonio Spurs for example, have had particularly tough schedules (facing opponents with an average win percentage of 0.511).  Others, like the Miami Heat, who have played many weak teams in the East, have had easier schedules (facing opponents with an average win percentage of 0.422).

In order to address the underlying concern of variability in schedules, I decided to recompute the win percentages for all teams in the NBA, taking into account the difficulty of each win and normalizing by the number of games played.  I looked at all games through Saturday, December 7th, and I defined “difficulty” of each win objectively as the opponent’s win percentage to date.  The recomputed numbers themselves do not have much intrinsic meaning other than their ordinality.  In other words, when sorted (by descending), this would provide a relative ranking of teams based solely on their wins and losses.  Here is the output from this relatively simple exercise (the green arrows indicate the magnitude by which a team’s simple Fanvana rank is better than its standard league rank and vice versa):


*The Bulls have lost Derrick Rose for the rest of the season and have had some victories against a depleted Heat team, so it is unclear how forward-looking this ranking will be.

This lightweight analysis proved to be fairly insightful, but it should not be confused with a “power ranking.”  Rather, I would like to highlight a few key takeaways:

1. Imbalance of Power

The Pacers have the best overall record in the NBA.  However, after adjusting for the difficulty of their opponents, the Blazers take the number one spot.  We will just have to wait and see if the Blazers can maintain this level of play throughout this season.  (Note: prior to their recent victory against the Spurs, the Pacers’ rank was a few more spots lower.)  The second best team in the East, the Heat, has also been displaced by one position to the sixth spot.  This is partly because of the imbalance of power between the two conferences, with the East having significantly weaker teams than the West.  Just to provide some perspective, even the Western Conference’s 13th (out of 15) ranked Minnesota Timberwolves would be a playoff contender in the Eastern Conference, if the playoffs were to begin today.  So far, 65% of the Pacers’ opponents and a whopping 80% of the Heat’s opponents have been Eastern Conference teams.

2. Hidden Gems in the West

There are a few teams that have either had impressive wins that were dwarfed by some other lackluster games or crazy schedules that deflated their win percentage (or a combination of the two).  These potential hidden gems in the Western Conference are the Phoenix Suns, Memphis Grizzlies, and Minnesota Timberwolves.

The Suns have played the Blazers three times already, and have beaten them twice.  They have also beaten the Rockets once.  However, they have also lost to some subpar teams like the Nets and Jazz.  They are also significantly better at home than on the road.  If the playoffs were to begin today, the Suns would not qualify, but I would not count them out—especially with the way the injury-riddled Warriors have been struggling so far.

The Grizzlies have not had too many spectacular wins, but they have had among the toughest schedules in the league (facing opponents with an average win percentage of 0.554).  Marc Gasol will be out for a few more weeks, but it will be interesting to see where the Grizzlies will stand at the All-Star break, or midway point of the season.  The Grizzlies are much better on the road than at home, in terms of win percentage.  However, that is a misleading stat because the skew is likely due to the fact that 58% of the games played before Gasol’s injury were on the road.

The Timberwolves have beaten the Mavericks twice and the *Westbrook-less* Thunder once.  They, too, have had a very tough schedule (facing opponents with an average win percentage of 0.557).  I am not saying that the T-Wolves are clear playoff contenders in the Western Conference, but they are definitely on the rise and may be able to snag the eighth seed.

3. Subtlety of Underperformance

Based on the adjusted Fanvana win percentage, there are a few teams that might actually be performing significantly worse than you would think by just glancing at the standings.  The teams that I will highlight are the Golden State Warriors, New Orleans Pelicans, Detroit Pistons, Washington Wizards, Charlotte Bobcats, and Toronto Raptors.

The young, injury-riddled Warriors have not had an easy schedule, but they have also beaten very few good teams so far.  In fact, only 25% of Golden State’s victories so far have been against teams with at least .500 records.  This is in contrast with the lower-ranked Phoenix Suns, who had roughly 36% of their wins coming from better than .500 teams.  Keeping in mind that the Dubs have had a few heartbreaking losses and unfortunate injuries, it is way too early to count them out.  However, the Suns are hot on their trail.

Another team in the Western Conference that I would like to flag is the New Orleans Pelicans.  Of the nine wins this team has, only one has been against a team with a better than .500 record.  In fact, if you look at the Pelicans’ schedule, 42% of opponents have been Eastern Conference teams.  In contrast, only 26% of the Los Angeles Lakers’ (who are one rank better than the Pelicans in the West, in terms of raw win percentage) opponents have been from the weaker conference.  With recently injured Anthony Davis out for at least the next month, it will be unlikely that we will see a turnaround any time soon.

The Eastern Conference is weak, but there are a few teams that may be even worse than we originally thought, win percentage-wise.  These teams include the Detroit Pistons, Washington Wizards, Charlotte Bobcats, and Toronto Raptors.  They have collectively accounted for only three wins against teams with a better than .500 record.  As expected, a majority of these teams’ opponents have been from the East.  The Bobcats, in particular, have faced an opponent from the same conference 80% of the time!  In addition to having weaker opponents, these teams just have not been able to get it done on the court.  For instance, the sixth-seeded Wizards suffered a recent loss to the Bucks, one of the worst teams in the league.

By re-weighting win-loss records based on an objective measure of difficulty for each win, we are able to have a better bird’s eye view of the relative performance of teams in the NBA.  Obviously, this technique does not take into account many key factors like win margins, home court advantage and injuries.  However, it does help tell a story that will hopefully make you a little more vigilant the next time you look at the standings.


One thought on “Adjusted Win Percentage: Where Does Your Team Stand?

  1. I did not expect Golden State’s adjusted ranking to be lower than their actual. This is pretty interesting. Maybe I only watch the games when they play good teams and am just desensitized to losing against them very narrowly.

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