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. 

Average Age

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
MEM    22.8978
POR    24.1397
CHI    24.7834
CHA    24.8325
MIN    25.0516
OKC    25.2086
UTA    25.2347
GSW    25.3229
MIA    25.3542
NJN    25.6025
ATL    25.8435
NYK    25.9501
MIL    26.0521
PHI    26.3214
SAC    26.5633
IND    26.7588
CLE    26.8154
LAL    26.9129
TOR    27.0772
WAS    27.2451
ORL    27.5021
LAC    27.5592
DEN    27.7794
NOH    27.9039
BOS    27.9651
DET    28.2222
HOU    28.3585
DAL    29.2533
PHO    29.5305
SAS    30.6093

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:
MEM    22.5476
POR    23.9251
OKC    24.4223
MIN    24.5981
CHI    24.7143
CHA    24.7957
UTA    25.0517
MIA    25.2547
GSW    25.5418
NYK    25.8768
NJN    25.9572
MIL    26.025
PHI    26.096
SAC    26.2507
CLE    26.2931
ATL    26.351
IND    26.6009
TOR    26.8093
WAS    27.1953
LAL    27.2098
DEN    27.2108
ORL    27.4351
LAC    27.6127
NOH    27.9389
HOU    28.1777
DET    28.5663
BOS    28.8435
DAL    28.9353
PHO    29.5283
SAS    29.8134

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:

via i37.tinypic.com

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:

via i37.tinypic.com

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:

via i35.tinypic.com

via i33.tinypic.com

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":

via i37.tinypic.com

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:

via i33.tinypic.com

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?