Wednesday, May 22, 2013

Age, Defense & Position

From the 1989-90 until 2011-2012 players selected to an All Defensive Team (average age 28.5) were about 1.5 years older than all other players (average age 27.0) in the NBA. The median difference was slightly larger at 3 years (29 for All Defense, 26 for all others). The question then becomes--Does the difference hold by position?

To measure this I categorized players over the last 23 seasons (excluding the 2012-13 season) into three positional groups based on their positions assigned in 'Point Guards' captured any player that was classified at one point as a point guard regardless of any other position he played during a given season. 'Post players' captured any player that was classified at one point as a center or power forward regardless of any other position he played during a given season. (Note: During these 23 seasons there were no players that were classified as point guards and power forwards or centers.) Finally, 'Wings' captured all other players (i.e., shooting guards and small forwards) that were not captured in the other two groups.

Admittedly, this isn't a perfect approach as there are players in a given season that played in more than one of these three categories. Examples include players, like Jalen Rose (2003-04) who played PG and SF, Mike Dunleavy (2006-07) and Kyle Korver (2007-08), who were assigned the positions of shooting guard and power forward, and any number of shooting guard-point guard combos, like Jarrett Jack, Kirk Hinrich, Bobby Jackson, Terry Dehere, and Shammond Williams. That being, said the approach represents a reasonable method for aggregating defensive players based on the offensive positions they are most likely to guard.

The first two charts below break out the mean and median for 'Point Guards'. It shows that for every season All Defensive PGs were at least the same age or up to 3 years older than all other PGs until a precipitous decline starting in the 2007-08 season, after which there is a gradual increase in All Defensive PGs over the next four years until last season where the two groups were about the same average and median age. (The sharp drop in the age of All Defensive PGs reflects that at the time third year players and 23 year olds Chris Paul in 2007-08 and Rajon Rondo in 2008-09 became regular All Defensive PGs.)

The next two charts break out the mean and median for 'Wings' (i.e., SGs and SFs). They show that except for the 1993-1994 season All Defensive wings were almost always older, and by quite a bit in the late 1990s, than all other wings. (The drop in 1993-94 is most explained by 23 year old Latrell Sprewell receiving his first and only All Defensive [Second] Team nomination.)

The final two charts show the mean and median for 'Post' players (i.e., PFs and Cs). Similar to Point Guards and Wings, All Defensive post players appeared to be older than all other post players except for about a 5 year stint starting with the 1999-2000 season, which reflects the beginning of a ten-year Tim Duncan and Kevin Garnett reign as first or second team PF and C. (The 1999-2000 season was Duncan's third and his third time on an All Defensive team and Garnett's fifth season and first on the team. Where Duncan entered the NBA after a four year college career and, thus, started his career at a later age than Garnett, Garnett entered the league straight out of high school but was only a month younger than Duncan despite his additional NBA experience.) Taken together the charts on the three groups suggest that with the exception of the emergence of a few precocious superstar defenders, across major defensive positional categories players nominated to an All Defensive Team tend to be older than all other players.

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