Semi-Random Weekend Thoughts

Posted on February 9, 2008 by

30


Here are a few semi-random weekend thoughts:

More on Shaq and Marion

A few days ago I posted a comment on the Shaq trade.  In this column was the following argument:

Let’s imagine that Shaq and Steve Kerr are right.  The issue was a lack of motivation in Miami and in Phoenix Shaq will return to the player we saw in 2004-05. That year Shaq posted a 0.306 WP48.  If that’s the O’Neal that arrives in Phoenix, will the Suns contend for a title in 2008?

Unfortunately, the answer is probably no.  Marion was already offering a 0.314 WP48.  So even if the old Shaq can become the Shaq of old, it’s not clear this team is better than the Lakers (with a healthy Bynum). They are certainly not better than the Boston Celtics.

Matthew Yglesias responded with this comment: Any Way You Look

The Yglesias post begins as follows:

It occurred to me that maybe Dave Berri has some counterintuitive argument as to why the Shaq-Matrix trade makes sense for Phoenix. The answer is no. Instead, he has a counterintuitive argument that even if Shaq were to return to his 2004-2005 season level of production the trade still wouldn’t help Phoenix. And, of course, that’s not going to happen.

When I read this I thought it would be worthwhile to elaborate briefly on the career performances of Shaq and Marion.  Entering this season, Marion had a career WP48 [Wins Produced per 48 minutes] of 0.303.  His peak was 2000-01, when his mark hit 0.414.  Despite this mark, in five seasons Marion’s WP48 ranged between 0.200 and 0.300. 

In contrast, Shaq’s average mark from 1992-93 to 2004-05 was 0.344.  In only one year did Shaq have a mark below 0.300 (1995-96) and his peak of 0.428 (1999-00) eclipsed the best mark of Marion.

In sum, if we compared Shaq’s career to Marion’s career, we would conclude that Shaq has been the more productive player.  I would emphasize, though, that the difference is not very large. If Shaq posts a 0.344 WP48 for the Suns in the second half of this season, Phoenix could expect to win about one more game (relative to what it would have received from Marion).

Of course, few people expect Shaq to return to what he was for much of his career. So this argument is probably not one we will be able to empirically check.

Value of Midpoint Analysis

We can, though, look at the evidence behind a related point.  Can we look at a player’s first half performance and know the remainder of the season?

Just like I did this year, in 2006-07 I downloaded each team’s data after 41 games.  Today I looked at the relationship between a player’s per-minute Win Score over the first half of the 2006-07 season and

1. the player’s per-minute Win Score in the second half of 2o06-07.

2. the player’s per-minute Win Score at the end of the 2006-07 season.

Looking at players who played at least 500 minutes in each half, for the first relationship – first and second half per-minute Win Score – I found a 0.84 correlation.  This is basically what you see when you look at performance from season-to-season, so again we have evidence that performance in the NBA is fairly consistent across time.

When we look at the second relationship – first half and final per-minute Win Score – we find a 0.96 correlation.  This is not too surprising, since half of the final mark is comprised of the first half numbers.  What it does tell us, though, is that what we have seen for the first half of the season from each player is roughly what we are going to see when the season is over.  So Dwight Howard can expect to win this year’s M2P [Most Productive Player] award (not that he gets anything for this).

Playoff Picture

Quick observation on the playoffs… right now the New Jersey Nets hold down the eight spot in the Eastern Conference with a mark of 21-29.  The Pacers, 76ers, Bulls, Bucks, and Bobcats are each posting marks that are even worse, yet each team can also claim it is within three games of the playoffs.  In other words, the Bucks – who I noted were expected to be a bad team this year – might still make the playoffs because so many bad teams play in the East.

In contrast, the Sacramento Kings are only three games below 0.500.  Such a mark would give the Kings the 7th seed in the East. But in the West, Sacramento is 6.5 games out of the playoffs and already dreaming of lottery balls.   

Roger Clemens Column

One final note… on Saturday Justin Wolfers gave me a heads up on his latest column.  Writing with three other Wharton School professors at the New York Times, Wolfers and company consider the statistical evidence that Roger Clemens did something he might regret.  Here is a link to their Keeping Score column:

Report Backing Clemens Chooses Its Facts Carefully

In addition to recommending this column, I would also recommend the work of JC Bradbury on this subject.   

– DJ

Our research on the NBA was summarized HERE.

The Technical Notes at wagesofwins.com provides substantially more information on the published research behind Wins Produced and Win Score

Wins Produced, Win Score, and PAWSmin are also discussed in the following posts:

Simple Models of Player Performance

Wins Produced vs. Win Score

What Wins Produced Says and What It Does Not Say

Introducing PAWSmin — and a Defense of Box Score Statistics

Finally, A Guide to Evaluating Models contains useful hints on how to interpret and evaluate statistical models.

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