One of the major themes of this seasons has been that the Blazers have been unusually successful for their age. I wanted to know, more precisely, just how young the Blazers are and just how successful they have been, given their age. So, I did a little research and found out. The answer? In short, they are one of the younger teams--though far from the youngest--and on pace to be by far the most successful team for its age in the past five years.
Most media sources call the Blazers the second youngest team in the NBA, with the Golden State Warriors being the youngest. This description comes from calculating the the average age of each roster in the NBA. As many people have pointed out, however, this is a less than ideal measure of age because some rosters have veterans or rookies that seldom or never play.
A better measure of a team's age, in my view, is the average age of the players on the floor. (To be more precise, define the average age of players on the floor as the expected value of the average age of the team on the floor from a randomly selected moment in the season). Believe it or not, this is relatively easy to calculate. It is just each player's Age * Minutes played divided by the total minutes played by the team.
Here are the average ages of teams calculated in that manner, with the teams currently projected to go to the playoffs by Hollinger in bold:
Team Average Age
As you can see, when calculating the average age of teams in this manner, the Blazers are indeed the second youngest team, but the youngest team is the Memphis Grizzlies (now, whenever you hear an announcer say the Warriors are the youngest team, you can snicker at their ignorance). It's also pretty damn clear that older teams, in general, are much more likely to make it to the playoffs.
Average Age Part 2: An Alternative Measure of Maturity
Now, some might think that even the average age of players on the floor is a less than ideal measure of what we really care about when we talk about the youth of a team--it's maturity as a basketball team. What if, for example, a team's stars are veterans and its younger players are role players? Certainly that is a more mature team than a team whose stars are young and whose veterans are role players, right? Perhaps. The only difficulty is that it's a little tricky to objectively determine who is a role player and who is a star. Nonethelss, in order to investigate if measuring the maturity team in some way dramatically changes the picture, I calculated teams' average age weighted by the number of field goals attempted (each players age*fga/total field goals attempted by the team). Think of this as the average age of the team's field goal attempts:
Team FGA weighted Age:
As you can see, this doesn't change the story too much. The Blazers are a little younger, but still the second youngest. This is primarily because Pryzbilla does not attempt a lot of field goals per minute. One of the teams whose ranking changes the most when calculating team age in this manner is, interestingly, Boston.
Win % by Average Age and FG weighted Age
The next thing I wanted to do was to get a better sense for where the Blazers stood in terms of the success given their age. To do this, I plotted team's win percentage this season against their average age and drew a (non-linear) regression line that shows (roughly) the average win percentage of a team, given their age:
The results are interesting. There is a pretty strong trend toward success (defined as win percentage) increasing with age up until a team's age reaches 28 or so. The top three teams in the league (Boston, LAL, and Cleveland) have an average age between 26 and 28, though so do some of the worst teams (Cllppers, and Wizards). The oldest teams, Dallas, Phoenix, and San Antonio, are all winners, but they are not the league's elite.
The Blazers are clearly the best 24 and under team and appear, to my eyes, to be on a trajectory towards joining the league's elite in the next couple of years. Of course, no one can be certain what the future will hold, and making projections into the future is dangerous, but it is easy to see why so many of us are optimistic about the future.
We see roughly the same picture if plot win percentage against teams' age weighted by field goal attempts. The only difference is, perhaps, a shortening of Boston's window for elite play:
Power Ranking by Average Age and FGA weighted Age
Since the Blazers have played such a difficult schedule, I also plotted the Sagarin power ratings against their age and FGA weighted age:
The same general conclusions seem to hold. The Blazers are ahead of the curve and on pace to join the league's elite. These graphs suggests, even more strongly, that there are diminishing returns to age (teams peak at 28 or so). In addition, I was amused to see that the teams that have fired their coaches are all significantly below the age-power ranking curve.
Age and Win % in the Past Five Seasons
Finally, I was curious to see if the age-success relationship that we see this season holds for previous season. And, I wanted to know if there had been any other teams as young as the Blazers that had been as successful. So, I put the data together for the past five season (2004-2005 to 2008-2009.... I could do more, and I might).
In the graph below, I plotted win percentage against team average age. I labeled Portland this season and last, as well as the nearest competitor for the title of "best young team in the last five years":
The only team in the past five years that could possible argue to be a better "young" team than the Blazers is the 04-05 Phoenix Suns. The average age of that Suns team was 25.1, a full year older than the Blazers. They were, however, led by the veteran Steve Nash, who was 30 years old by the end of the season. So, I give the title of best young team in the last five years to this years' Blazers.
UPDATE: Age and Win % in the Past 10 Seasons
I had a little more time this afternoon and added five additional seasons. And, because some were interested, I marked which teams eventually won the NBA championship in each season (they are the black diamonds). With five years of additional data, the 2008-2009 Blazers still stick out:
Lastly, a question to ponder and discuss: the age success relationship appears to only get stronger as I add more data; why aren't there more older teams in the NBA?