First, we’ll establish the premise. It’s not just hyperbole to suggest that the Bulls have been the best defensive team since Thibodeau came on board. Their league-leading 100.7 defensive rating over the last three seasons combined, per Basketball-Reference, establishes that.
And this year they started off similarly. They had the fourth-best defensive rating in the Association up through the All-Star break, continuing to play as one of the league’s elite defensive teams in spite of injuries, according to NBA.com (account required).
However, after that the defense seemed to fall apart, falling to 11th for the duration of the season, with the Bulls giving up more than five points per 100 possessions more after the break than before it.
What caused the defensive collapse in Chicago, and does it suggest that there could be more trouble ahead for the team?
Ultimately, no matter how well a defensive design works, it depends on the players’ ability to execute the system, and their willingness to commit to it. Not all players on the Bulls are created equally though, at least as it pertains to defensive acumen.
Based on their net defensve ratings (data obatined from 82games.com), here is the estimated number of points per game each of the Bulls who played at least 10 percent of the team’s minutes cost or saved the team per game they played last season:
There were three players who had a decidedly negative impact on the team, costing the Bulls more than a point per game: Carlos Boozer, Marco Belinelli and Nate Robinson.
There were another four, Luol Deng, Jimmy Butler, Richard Hamilton and Nazr Mohammed, who had a neutral impact on the team.
In part, Deng and Butler had a neutral impact because they filled in for one another, and since they’re comparable defensively, they offset one another. In other words, saying they were neutral doesn’t mean they’re average. They just averaged out.
There were four players, Taj Gibson, Marquis Teague, Joakim Noah and Kirk Hinrich, who had a positive impact on the team.
Without going into a ton of detail, after the All-Star Game, the Bulls were obliterated by injuries. They had some before that, but aftewards, it was insane. Look at this pie chart which shows how the minutes were broken out prior to the festivities, by percentages:
Note how overall the team’s best defenders played a lower percentage of the minutes, and the players who were a liability played a larger chunk of the minutes.
Now, look at how that shifted after the break:
Carlos Boozer played two percent more minutes, as did Nate Robinson. The end of the bench played one percent of the available minutes early, but three percent later.
By contrast, Joakim Noah fell off from 14 percent to 12 percent. Taj Gibson dropped from nine percent to four percent. Richard Hamilton, who had a more positive than defensive effect than advertised, went from seven percent to one percent.
When your best defensive players go out and get replaced by your worst defensive players, your defense is going to get worse. This is in the “no duh” category of argument.
When you put the minutes together, you get a compelling picture. Here’s what happened to the Bulls in terms of positive, neutral and negative minutes before and after the split:
Before they started collecting injuries like they were some newfangled version of stamps, the Bulls had the most minutes from their best defensive players and the fewest from their worst defensive players.
After the break, however, that changed. Their worst defenders played nearly twice as many minutes as their best.
It stands to reason that what happened is that the Bulls lost their better defenders, and that’s why they lost their stalwart defense.
The Bulls have since jettisoned their two most deplorable defenders, Marco Belinelli (who was still appreciated for his late-game heroics) and Nate Robinson (who was still appreciated for his postseason heroics).
Carlos Boozer is in that conversation, but his 690 defensive plays (total steals, blocks and defensive rebounds) were the 18th-most (original research) in the NBA. At least with Boozer, there’s some positive contribution, even if getting past him is like trying to get past a slow and lethargic tree.
In their places will be Mike Dunleavy and Derrick Rose.
With Rose, Ronnie Brewer, Deng, Boozer and Noah in 2012, the Bulls had the best defensive unit with at least 250 minutes played, per Basketball-Reference. Assuming, quite reasonably, that Butler can equal what Brewer did, the starting five should be fine next year with Rose replacing Robinson.
Where will the Bulls finish in Defensive Rating next year?
Off the bench, the Bulls will have an upgrade over Belinelli in Dunleavy. His Milwaukee Bucks were .8 points better defensively last year. Prior to that, they were 5.6 better in 2011. His Indiana Pacers were 4.0 better in 2010.
In all, in six of the last seven seasons, his teams were better defensively while he was on the court. That’s not saying he’s going to make the All-Defense team, but he is an upgrade over Belinelli, who defended like a mosquito defends a windshield of a Texas-sized SUV traveling 80 MPH.
Former All-Defense player Kirk Hinrich and defensive specialist Taj Gibson will also be coming off the bench, and they should be able to lead the second unit defensively. Nazr Mohammed learned the defense over the course of last season, and while he never became an asset defensively, he at least stopped being a detriment.
Marquis Teague will need to continue to show the type of improvement he displayed in Las Vegas to accrue more minutes, but last year’s net defensive ratings were encouraging, if confusing.
Tony Snell is made from the Jimmy Butler/Luol Deng mold of defender, in that he has a massive 6’11.5” wingspan, per ESPN, and great defensive instincts. It may take him, as well as fellow rookie Erik Murphy, time to see the court.
The Bulls do have defensive questions at the end of their bench this year. They have more talent there, but it’s much younger and inexperienced. They have more talent and experience in the rotation, though.
As with all things Bulls these days, you must include the qualifier, “provided they stay healthy.” If they do, they should reclaim their spot as one of the league’s elite defensive teams and battle it out with the Indiana Pacers and Memphis Grizzlies for the title of stingiest team in the league.