From Mike Kurylo of Knickerblogger.net — Do Stats Lie?

This is from Mike Kurylo of Knickerblogger.net. Mike’s post is called: Do Stats Lie? 

Yes, I didn’t write this. And yes, I am cheating here.  Normally the WoW Journal only posts stuff written for the WoW Journal (not much re-posting here).  But I thought this was a good explanation of offensive efficiency and it relates to something I said about the Denver Nuggets earlier in the week. Furthermore,  Wins Produced is built on offensive and defensive efficiency, and it may not be the case that these concepts are well understood.

So here you go (and yes, I will post something I wrote — specifically the QB Score rankings of the week — later today).

Do Stats Lie?

by Mike Kurylo

Lately I’ve been thinking about the greatest offensive team of the last 20 years. Led by Michael Adams and Orlando Woolridge the mighty 1991 Denver Nuggets punished opponents by scoring 119.9 points a night. That Nuggets offense just beats out the the 1992 Mullin-Hardaway Warriors (118.7 pts/g) and the 1989 Chambers-K.J. Suns (118.6 pts/g). Certainly since the 1991 Denver Nuggets scored more points per game than any team since 1987, they were the NBA’s best offense in that timespan.

Or are they? This seems to be a dubious claim. Looking at the 1991 Nuggets, none of the players were voted to the All Star team that year. There aren’t any Hall of Famers on that team. Denver went a rancid 20-62 that year. Of the three teams above, there are no champions. No Michael Jordan. No Magic Johnson. No Larry Bird. No Shaq. No Steve Nash.

How can a 20-win team be one of the great offensive teams of all time? You might say that the stats are “lying” because they’re misrepresenting what we believe to be true. But that’s not the case. The numbers are 100% accurate. If you watched every game of the last 20 years, you would not have found a team that scored more points in a season than the 1991 Nuggets. Saying the 1991 Nuggets scored the most points per game in the last 20 years is true. Saying the 1991 Nuggets are the best offensive team in the last 20 years is false. The deception is in the interpretation of the statistics, not in the stats themselves. The problem is in equating “most points per game” with “best offensive team”. The correct interpretation for “most points per game” is “most bountiful offense”, which is quite different from “best offensive team”.

Take this example: Going into the 2007 season, the Chicago Bears have a good chance to win the Super Bowl. One vegas line has their odds at 8-1 to win it all. One of their best players is Rex Grossman who has a fantastic 17-5 record as a starting QB.

Once you pick yourself off the floor laughing, it’s easy to see where the fallacy is. The Bears do have a good chance to win the Super Bowl this year. Their odds to win, at least from one vegas site, is 8-1. Rex Grossman has a 17-5 record as a starter. All these things are true. However they’re not one of the best teams in the NFL due to their QB. Rex Grossman is by all accounts a bad quarterback. Carson Palmer, an All Pro, has a winning percentage of only 55.6%. The deception is in saying that QB win percentage indicates the quality of the QB. There are better ways to judge the ability of a QB like completion percentage, TD-INT ratio, yards per attempt, etc.

Getting back to our original example, those 1991 Nuggets scored so many points per game because they ran a very fast offense (and also a very fast defense). Denver led the league in pace averaging 113.7 possessions per game. To show how much an aberration this was, the league average was only 97.8 and the second fastest team was the Golden State Warriors at 103.6 possessions per game. A team can increase its points per game by simply increasing its pace. This reveals a flaw in the relationship between “points per game” and “best offense.” It’s obvious that points per game isn’t the best measure of a team’s offensive capability.

To more accurately judge which team had the best offense, you need to account for this disparity in possessions per game. Offensive efficiency, sometimes known as offensive rating, calculates how many points a team scores per possession (or more accurately 100 possessions). The importance of offensive efficiency is that it evens the playing field between the fast and slow paced teams. The 1991 Nuggets had an offensive efficiency of 105.2, which placed them 21st out of 27 teams that year. The best offensive team in 1991? The Chicago Bulls, who scored 114.9 points per 100 possessions. This was Jordan’s first championship team, and clearly they were better than the Nuggets on offense that year.

In the end, stats don’t lie. They are numerical records of history. The 1991 Denver Nuggets did score 119.9 points per game. Rex Grossman had a record of 17-5 as a starter going into 2007. The problem is not in the numbers, but rather the people that use these statistics to make claims that they don’t support.

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