Statistical Analysis. Humor. Knicks.

Thursday, December 18, 2014

Do Stats Lie?

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.


Extras:

  • For more information on points per possession, check out Dean Oliver’s excellent book: Basketball On Paper. Or read this and that.
  • During the season I keep track of offensive efficiency on the stats page. Historical offensive efficiency can be found at basketball-reference.com
  • The team with the highest offensive efficiency over the last 20 years? The 1996 Bulls at 115.8. Does this make them the best offensive team of the last 20 years? Well you might want to account for league average, but that’s a discussion for another day.
  • For more information on the 1991 Nuggets, see this link.
  • For a really good way to rate QBs, I would use DVOA.

13 comments on “Do Stats Lie?

  1. Mike G

    The people who say ‘numbers lie’ are usually people who like to lie with words. This goes back at least as far as Mark Twain.

    Now that we have ready access to ‘advanced stats’, we should be free from deceptive numbers — right?
    I’ve always alluded to those ’91 Nuggets as an example of ‘when not to take averages at face value’.

    On this page:
    http://www.basketball-reference.com/leagues/NBA_1991_t.html
    scrolling way, way, down to ‘Rebound Rate’ leaders for 1991, you see Jerome Lane (of Den) ranking 4th, at 19.7 . This just means he got 19.7% of all available rebounds.

    But Denver was outrebounded that year by an average 52.5 – 49.4 per game. They were a weak rebounding team, so I think all their players have inflated RebRts. Adjust Lane’s RbRt by the factor 49.4/52.5, and he’s only #8, at 18.5 .

    Is PER a ‘true’ stat? The ’91 Nuggs placed Michael Adams (22.3) #11 in the league. This is ahead of Drexler (in a good year), TPorter (his career year), Mullin (almost his best), Reggie (career high), Tim Hardaway (ditto), etc. Both Adams and Woolridge, according to PER, suddenly got much better, just for that season.

    While some of these improved stats adjust for ‘pace’, they don’t consider whether a guy’s team is getting killed on the boards or slaughtered on the scoreboard. I for one don’t believe players get better when they stop boarding or playing D.

    The way a team can be the highest scoring team in decades, yet go 20-62, is by allowing an unconscionable 131 PPG. The ratio of Den/Opp PPG is 120/131, or 91.6%. Multiplying Den PER’s by this figure would go a long way towards correcting their inflated values.

  2. Hudson River

    Nice Article.

    I’ve always been a fan of the Points Per Possession stat (Or per 100), It is the only accurate way to take into account the efficiency a team rebounds the ball on offense, turnovers, and free throws. It seems so simple, but the stat is the best way to identify the best offensive teams. The Phoenix Suns, clearly best volume scorer is also the best in terms of efficiency, which is very impressive. The Mavericks are the second most efficient offensive teams, followed by the Western Conference finals.

    The Utah Jazz were the 3rd most efficient Offensive team last year. Their Defense was ranked 19th in the league (Behind the Suns, Warriors, and the Celtics). The Jazz relied on their offense, not their Defense. This proves that a slow offense where teammates are unselfish and pass and cut can be extremely effective. They made it to the Western Conference Finals with the Defense worse than the Warriors, and Celtics.

    The Spurs had a ranking of 4th in the league, ahead of the Warriors, Wizards, and the Nuggets. Two teams whose offenses were thought to be their weak-points (although technically the 4th rated offense was the Spurs weakness: Their D was ranked 2nd after the Bulls.)

    The Spurs challengers in the Finals, The Cavs had an Offensive ranking of 19, and a defensive ranking of 4. Maybe its not as simple as Defense (+ a superstar) wins championships. Again, great article.

  3. Adam F

    Interesting article. Really makes me reconsider the importance of looking at things “per 100 possessions”.

    By the way:

    “They featured 6 players who scored 20+ points per game.”

    That’s just not true. They only had 2.

  4. Mike

    Stats by themselves do not lie but people use stats to lie often. Usually they decide on a point they want to make and then seek only stats that back up that point.
    Eddy Curry is one of the most accurate 3 point shooters in league history. He has never missed a 3 point shot in his career shooting 100%.

    Did the 100% stat lie? No. I just used the stat without context to tell a story that is deceiving.

  5. Nathan

    Even if that wasn’t a good team, that Nuggets team had the right idea. If you have to be a bad team, at least have the decency to be entertaining while you’re at it. I don’t want to watch the Atlanta Hawks lose game after game 70-80, I want to see them lose 120-130.

  6. retropkid

    Do stats lie?

    Nah.

    Now, Zeke lies. And Dolan lies. Marbury lays… so does his cousin (shared service interns, an MSG special…).

    But stats? No, they don’t lie. But they don’t tell the truth either…they just sit there waiting to be manufactured and manipulated by liars, soothsayers, truth-tellers and everybody in between….

  7. Frank O.

    Heads up all.
    Shawn Marion on the block
    Another guy that would be nice to have, but we couldn’t get…

    Arizona Republic –
    After eight years in Phoenix, Shawn Marion wants to leave the Suns and has let the team know in recent weeks.

    “I’m tired of hearing my name in trades,” Marion said by phone from his Chicago home Tuesday night. “I love my fans in Phoenix but I think it’s time for me to move on.”

    There are two known trade suitors in the Utah Jazz (for Andrei Kirilenko, if not others) and the Los Angeles Lakers (for Lamar Odom and a teammate), with Marion showing an interest in the latter because of a friendship with Kobe Bryant.

    “Regardless of everything that went on with the extension, I’m tired of hearing my name in trade rumors,” Marion said. “It’s time for me to move on. I felt like they tried to force my hand to Boston with the (Kevin) Garnett stuff.”

    In June, there was the possibility of a three-way trade sending Garnett to Phoenix, a Boston pick package going to Minnesota and Marion to Boston with a contract extension but the Marion camp killed it.

    “I haven’t done anything wrong,” said Marion, a four-time All-Star. “I leave it on the floor night in and night out. Sometimes, it’s just time, and it’s time to go. “It’s been like a nightmare. It hurts me making this phone call. It’s hurting me in my stomach.”

  8. Frank O.

    He would be a perfect fit at SF for the Knicks.
    6’7, agile. He gets almost 2 bpgs, Knocks down 17 a game, without anyone running him a play, grabs about 10 rpgs. His D is totally underrated.
    He’d be a great acqusition.
    Problem is he’s expensive $49 mil over three.

  9. xduckshoex

    Part of the reason he wants out is managements refusal to negotiate an extension with him. Apparently that $49 million over three years isn’t enough for him, he wants $60 million.

  10. Frank O.

    Mark Twain once said “There are three kinds of lies: lies, damned lies and statistics.”

    That about sums up my opinion…

  11. Ted Nelson

    -I?ll cast my vote on the side of those who have been saying that it?s all about the interpretation of the stats.

    -It seems like no other player is as controversial as Marion in terms of being over-/under- rated. A trade could potentially help decide the debate, but I?m holding my breath because I anticipate that both Marion and the Suns can survive without each other. Who the Suns, potentially, replace him with and how that change effects their championship aspirations should also be interesting.

    -I?ve been working on a website to provide advanced stats for the Spanish ACB league as well as some blogging (to come): easyasacb.wordpress.com. It?s a work in progress, but I?d love to get some feedback (including whether you think the name is too corny).
    I realize most Americans, and even most Spaniards, could care less about the ACB, and I?m sure most of you won?t be checking it out as much as you might this site or another NBA site. However, I think there are a few reasons to check it out every once in a while.

    First, you can check out some guys with the potential to make a big impact in the NBA down the road or keep up with guy you watched play in the NCAA or NBA.
    -Both Luis Scola and Juan Carlos Navarro are making the jump to the NBA this season, so you can check out how they did last season.
    -You can check out the 06-07 seasons of and follow the 07-08 seasons of Rudy Fernandez, Tiago Splitter, and Marc Gasol, all of whom were picked in the 2007 NBA Draft. As well as several other players, listed on the site, whose draft rights are held by NBA teams from previous drafts.
    -Some former NCAA and NBA players including Louis Bullock, Marcus Fizer, former Knicks Bruno Sundov and DeMarco Johnson, Jerome Moiso, Skita? played in the ACB in 06-07.
    -Ricky Rubio, Victor Claver, and Goran Dragic are a few of the top young prospects you?re likely to see in the NBA in a few years.
    -Most importantly?you can keep up with our buddy FRED WEIS, who plays for Bilbao.

    The stats themselves should be pretty interesting. I haven?t done much of anything with them, but I assume there?s a lot that could be learned?and there are some people on this site and elsewhere who are certainly more capable of analyzing these things than I am.

    I?m also going to try to offer some interesting articles on international basketball, and hopefully spark some discussions on the level of those here on Knickerblogger. In the coming weeks I?m planning on posting an ACB offseason review, a season preview, an NBA offseason review, and some other articles.

    Anyway, the site is easyasacb.wordpress.com

    *****Owen, I am planning on adding WOW stats, but haven?t gotten to it.

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