The Bulls Forget How to Score

The Disappointment of the 2007-08 season has been the Chicago Bulls. Chicago was expected to contend with the Boston Celtics in the Eastern Conference.  Yes, I thought the Celtics would be better, but I thought the Bulls were clearly the second best team in the conference before the season started.  Instead, this team is the worst team in the conference. You can see it in the won-loss record.  And you can see it in the team’s efficiency differential (offensive efficiency minus defensive efficiency) which currently stands at -8.5.

When we look at defensive efficiency, we see a team allowing 97.4 points per 100 possessions. This is virtually identical to what we saw in 2006-07 (97.0 points per 100 possessions).  On the offensive end, though, we see a team that’s only scoring 88.9 points per 100 possessions.  Last year, with virtually the same roster, this team scored 102.2 points per 100 possessions.  So what the hell happened?

John Hollinger wrote a very good column detailing this team’s woes.  In case you didn’t read it (it is an Insider Column), I will give you the basic argument in one sentence. Chicago has forgotten how to get the ball to go through the hoop.

To see this, consider points-per-shot {or points-per-field goal attempt, or [(PTS-FTM)/FGA, or Adjusted Field Goal percentage*2, these are all the same thing}. Last year the Bulls scored 0.99 points per field goal attempt.  This year the Bulls are only scoring 0.83 points per field goal attempt. 

To see the impact all these errant shots have had on the Bulls, I made three projections for this team.

The first is how many wins the Bulls could expect this year if each player (except the rookies) performed on a per-minute basis as they did in 2006-07.  The second projection takes only the shooting efficiency (points-per-shot again) from 2006-07, but leaves everything else in a player’s performance exactly as it is this season.  And the last projection is based solely on what the players are doing this season.  All three projections are reported in Table One.

Table One: Projecting the Chicago Bulls

As Table One reports, had the each Chicago player maintained what they did last year, the Bulls would be on pace to win 57 games. This would not be good enough to catch Boston or Orlando, but it would put this team in the thick of the Eastern Conference title chase.

What happens if all we only utilize shooting efficiency from 2006-07, but keep everything else as it is in 2007-08?  Now we see the Bulls would be on pace to win 55 games.  Yes, virtually the entire problem this team has is tied to shooting efficiency.  If this problem were solved, this team would start winning again.

Without this problem being solved, we can see that this is going to be a very sad season.  If the Bulls maintain their current shooting problems, we can expect this team to win between 18 and 19 games.

Let’s summarize what we’ve learned.  Although people have argued that scoring doesn’t matter much in calculating Wins Produced, we see evidence in this story that a team can dramatically alter Wins Produced simply by changing shooting efficiency.  Rebounds, steals, turnovers, etc… can all stay the same, but if the shots don’t go in the team will have trouble winning.  Of course, if a team keeps shooting efficiency the same but forgets about rebounds, steals, turnovers, etc…, the team will also have problems. But that’s a story for another day.

Let me make four more observations.

1. At least half of this team’s decline is tied to the performance of Kirk Hinrich and Ben Gordon.  That being said, the shooting woes have inflicted the entire roster.  So this is not an issue with just one or two players. 

2. I don’t know why the shots aren’t going on.  We can look at the numbers and see where a team’s problems are (or are not). But the numbers alone are not going to tell us why.  In sum, the numbers are not going to do your thinking for you.

3.  I would note that this could be entirely a small sample problem.  After all, this team has only played 13 games.  Because this stretch happened at the beginning of the season it’s very noticeable.  A similar streak in mid-season would not be quite the same story. 

4. Ben Wallace has played somewhat worse, but I think his decline has been somewhat over-stated.  Overall his WP48 has declined from 0.210 to 0.165.  But I think part of this is due to how badly he played the first week of the season when he was playing hurt.  My sense is a healthy Big Ben will still produce wins this year. 

Of course, if this team doesn’t hit its shots, all of Big Ben’s production isn’t going to get this team into the playoffs.

– 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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