When Will We Know About Greg Oden?

On Friday I compared the performance of the top pick in the NBA draft to the performance of the most productive player selected in each draft since 1991. Or as I put it – I compared The Top Pick vs. The Top Pick.

In this post was the following table, which detailed the career performance of each number one pick since 1991.

Table One: The Career Performance of the Number One Picks (1991-2006)

Now back in May I wrote a column examining the value of having the number one pick in the draft. In that post was a table that reported the productivity of each number one choice his rookie season (since 1992).

Table Two: Performance of Number One Picks – 1992 to 2007

Today I want to put these two tables together. Specifically I want to compare what the number one picks did their rookie season to what they did the rest of their career. For this we turn to Table Three.

Table Three: Evaluating the Consistencey of the Number One Picks – 1991-2005

Table Three compares the productivity of each number one pick his rookie season– measured via WP48 (Wins Produced per 48 minutes) – to what that player did after his first year.

Across the past 16 seasons we see that the number one pick posted a WP48 above 0.100, or above average, nine times. Of these nine players, only Joe Smith failed to be above average the rest of his career. Five players posted a WP48 in excess of 0.200 their rookie season and only Chris Webber – whose career numbers have declined since his injury in 2003 – failed to post a career WP48 in excess of 0.200. In sum, virtually all the “good” rookies have been “good”. And the “great” rookies were generally “great.”

At the other end of the table are many of the top picks who did not have stellar careers. Seven players have been below average their rookie season, but Andrea Bargnani has yet to have a career beyond his first season so he is excluded from the analysis. Such analysis suggests, though, that Bargnani might not be worthy of his number one selection. When we look at the career performance of the six below average players we see five players who went on to post below average career numbers. The lone exception, LeBron James, was virtually average his rookie season and went on to be extremely productive.

Ideally we would do more than just stare at the numbers. Unfortunately our sample is only 15 players, which is a bit small for us to do any real analysis statistically. Still I would note that the correlation coefficient between First Year WP48 and After First Year WP48 is 0.79.

These numbers do “suggest” – and I want to emphasize the word “suggest” – that we might be able to tell a great deal about Greg Oden by the end of the 2007-08 season. If Oden fails to deliver an above average performance his rookie season, it would be fighting a trend for him to suddenly deliver later on. And as noted above, the same story can be told about Bargnani.

Again the word is “suggest.” A sample this small cannot provide us “proof” or the “truth” (not that we are in the “truth” business).

Looking at a Larger Sample

What would be interesting to see is the predicitive power of the first year performance for all players. And I wasn’t planning on looking at this today, but looking at the data I have collected I decided this would only take a few minutes.

So after a few minutes of analysis I found a 0.69 correlation between first year WP48 and WP48 after the first season (for all drafted players since 1991 who played at least 800 minutes his rookie season). In sum, if all we know about a player is his rookie year per-minute performance, we know a great deal about what that player will do the rest of his career.

In other words, even if we don’t know about a player’s injury status, his role on his team, his coaching, his attitude, his shoe deal, etc… we still know much about a player’s career performance if we simply know what he offered his first few games as an NBA player.

Let me put this in perspective. The correlation coefficient between a baseball batter’s OPS this season and last season is less than 0.60. In football the correlation between this season and last season’s performance for a quarterback is less than 0.4o. So we are seeing more consistency between what an NBA player does his rookie season and the rest of his career than we see from year-to-year in baseball or football.

The consistencey of NBA performance is one of the more important stories the statistical analysis of the NBA reveals. Relative to baseball and football, what you see is much closer to what you are going to get in the NBA. This consistency may be bad news for Bargnani fans, but it should be good news for decision-makers in professional basketball.

– DJ

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