With Phoenix's dominant run through the 2014 WNBA season and playoffs, fans and journalists are asking where this version of the Phoenix Mercury ranks among the WNBA's all time teams.
Are they greater than, say, the "Worst to First" Detroit Shock? Would they have beaten those championship Los Angeles Sparks teams with Lisa Leslie in the peak of her form? Could they have challenged the four-peat Houston Comets?
That's a question best left to philosophers, but there is a way one can compare teams across different times and even different eras, since we're almost a full generation away from the 1997 season. One way to do this is through standard deviation. I've written a lot about standard deviation, but the main idea is to look at how far away a given team is from the "average" team, depending on how you define average.
The best of 2014
Let's look at the finish of the 2014 WNBA season. Teams are ranked by win-loss record. I'll explain what all of these numbers are, but here is the table.
Teams, obviously, are on the left. The "x by Phoenix indicates that they are the title winners. In the WNBA's 18 seasons, the team with the best win-loss record has won the championship 12 times.
The numbers in the second column are wins, and the numbers in the third column are losses. The numbers in the final row serve as a check. There are 204 total wins and 204 total losses.
(An important note: we are not looking at any playoff wins or losses. We are only looking at regular season results. The goal is to determine how dominant a team is over its counterparts.)
The numbers in the fourth columns are win percentage (wins divided by wins plus losses). But if you go to the last row, that 0.151 value is clearly NOT the win percentage of 204 wins and 2014 losses. So what is it?
0.151 is the standard deviation of winning percentage. It's the square root of the sum of the squares of the differences between each of the values in the fourth column and the average of the values in the fourth column. I can sense you're falling asleep, so I'll just state that 0.151 is the "unit of spread" and be done with it.
The numbers in the fifth column explain how many units of spread the win percentage in the fourth column are away from a percentage of 0.500. In Phoenix's case, (0.853-0.5)/0.151 = 2.337. This gives us a measure of how far away the 2014 Phoenix Mercury are away from a hypothetical average team in 2014.
The most dominant teams ever
If we do this for every team in every season of the WNBA, how does the 2.337 of the Phoenix Mercury compare to other great teams?
|Best Teams by Standard Deviation Method|
|2||2001||Los Angeles Sparks||2.185|
|4||2004||Los Angeles Sparks||2.177|
|5||2000||Los Angeles Sparks||2.034|
|6||2002||Los Angeles Sparks||1.942|
According to this method, the 2014 Phoenix Mercury are indeed the greatest team of all time. They rank higher than a number of notable teams. Also note that the team at #14 is the 2014 Minnesota Lynx. The last time we had two teams that were at least 1.5 standard deviations above the mean win percentage in the same season was in 2009, when the Phoenix Mercury (1.823) took on the Indiana Fever (1.519) in the WNBA Finals.
Obviously, it would be the greatest Phoenix Mercury team ever under this ranking system. What you might not recognize is that this year's Minnesota Lynx team would also rank as the greatest Lynx team ever. None of the previous teams broke the 1.5 standard deviations barrier; the closest was the 2011 Lynx at 1.489 would previously ranked at the best Lynx team.
The worst teams ever
Of course, we can work the same magic to see what the worst WNBA teams of all time were. Which WNBA teams have been at least 1.5 standard deviations below the mean in winning percentage?
|Worst Teams by Standard Deviation Method|
|2||2004||San Antonio Silver Stars||-2.177|
|10||2005||San Antonio Silver Stars||-1.715|
|17||2007||Los Angeles Sparks||-1.569|
Yes, I can still proudly say that the 2008 Atlanta Dream really were the worst team ever. Note that Connecticut, Indiana, and New York might have had bad teams in their history, but have never had a truly terrible team by this method. Washington has had more truly bad teams than any other WNBA team.
Given all of the above, we now use some of the same math to look at the competitiveness level of the 2014 season. You could make the argument that the 2014 season wasn't competitive at all, given that Phoenix and Minnesota galloped out to commanding leads. On the other hand, you could argue that the Eastern Conference was extremely competitive, with lots of teams in the middle and the final playoff spots not decided until the very end.
The number at the far right of the first table - that 1.76 - is the Noll-Scully value of the 2014 season. I wrote about Noll-Scully a long time ago at my old blog. The general rule is that a league whose wins and losses are determined by random chance won't have every team finish with a .500 record for the same reason than when you flip a coin four times you won't always get two heads and two tails. If you determine wins and losses randomly, some teams will have higher win percentages than others due to random chance.
Noll-Scully compares this imaginary coin-flip league to any given league and determines the difference. If a league's Noll-Scully measure is equal to 1.00, it would be exactly equivalent to wins and losses being determined randomly. The smaller the Noll-Scully measure is to one the harder it is to get a win (the wins might as well be distributed randomly), the bigger the Noll-Scully measure is the less competitive the league.
Here are some commonly accepted Noll-Scully measures for professional leagues.
National Football League: 1.48
National Hockey League: 1.70
National League (baseball): 1.76
American League (baseball): 1.78
National Basketball Association: 2.8
The 2014 WNBA season was equivalent to that of say, your average baseball season. In terms of WNBA seasons in competitiveness, it's somewhere in the middle. Noll-Scully measures in WNBA history have ranged from a low of 1.13 (!!) in 2009 to a 2.60 in 1998.
If you weight the most recent seasons higher than the most distant ones, the average Noll-Scully measure of the WNBA as a whole is 1.87. It's higher than most professional sports but nowhere near as high as that of the NBA. In the WNBA, every team has a chance to win, something which critics say can't be said of the NBA.
Most likely, none of the above math will change anyone's mind, except in those cases where it confirms some passionately held belief. Even math fans like myself are warned not to use math tricks the way a drunk uses a lamppost, i. e. for support instead of the proper purpose of illumination. I think one thing we can all conclude - math or not - is that the 2014 Phoenix Mercury was a spectacular team and the 2014 Western Conference Finals was a spectacular event, and hopefully next season will allow WNBA events which are just as bright to shine in the sky of a crowded sports world.
For more on the 2014 WNBA Finals, check out our Mercury vs. Sky storystream.