One of the big concerns about Carlos Boozer coming back to the Bulls was his impact on the defense. Boozer hasn't ever been known as much of a defender, and quite honestly, hasn't played a whole ton of defense since returning to the lineup either. However, Boozer's return to the lineup hasn't hurt the defense at all, in fact, the defense is playing better than ever, particularly at the close of games.
What's more, it's so clear that the players have been coached up. That as time goes on in practice, they have learned to execute the system better, made faster rotations, and covered up on their man. The Bulls have been particularly strong in the clutch defensively recently.
How do you measure defense?
Forget the BS stats like FG% defense which means nothing if you give up lots of threes and foul the hell out of your opponent. The Bulls are 3rd in the NBA in defensive rating which measures how many points they give up per possession. It is the be all end all of defensive stats, because it balances out everything to determine which team gives up more points adjusted for pace and everything else.
How good have they been recently?
The Lakers, Pacers, 76ers, Wizards, and Timberwolves were all held to season lows (at the time of defeat) against the Bulls in the past seven games. That's right five of the past seven opponents scored a season low against us. Prior to that, the Bulls were just two points off holding Cleveland to a season low and held the Thunder to just 90 points.
Who's making the difference?
It's been a team effort, great coaching, great scheme, and good execution. Guys who look like defensive sieves like Korver have done an admirable job staying in front of their man and forcing tough shots. Kurt Thomas has played outstanding defense the past couple games to step up for Joakim Noah and Taj Gibson. Luol Deng has been consistently very good defending the perimeter. C.J. Watson has been a train wreck offensively, but has gotten after it defensively.
We can't forget Joakim Noah just because he had surgery, his defense was outstanding earlier in the season and his ability to defend the pick and roll separates him from the vast majority of other big men in the NBA. Taj Gibson plays a similar style to Noah just with a bit less size and athleticism on the glass and also defends the pick and roll well. Both players have done an excellent job rotating to provide interior help on slashers as well.
Recently, the one guy that has really stood out to me is Ronnie Brewer though. He's spent a tremendous amount of energy chasing guys through screens, disrupting the passing lanes and doing his best to lock guys down. There are times where Brewer's presence on the floor forces huge delays for the opponent to get in the offense as he tips and denies passes and forces his man to give up the ball.
In the end it's the coaching
The Bulls have a lot of solid defensive players, but they also play relatively weak defenders for huge minutes each game. Derrick Rose is capable of playing great man on man defense, but he frequently gets lost on pick and rolls and seems to save himself for offense at times. Carlos Boozer looks to rebound more than defend and doesn't add much to that end of the court. Kyle Korver's been viewed as a horrible liability on defense for his whole career.
Looking at the Bulls talent, nothing about the players leads you to believe they'd be an elite defensive unit in the league. Many teams have pieces like Brewer while Noah and Gibson can block shots and play with speed but both can get beasted inside. Luol Deng and Keith Bogans are functional defenders but haven't ever been viewed as lock down guys while the rest of the rotation is made up of players with poor reputations defensively (Rose, Boozer, Korver).
The Bulls play with a fairly even mix of offensive and defensive talent, but Thibodeau has merged the group into one of the premier defensive teams in the league. Credit the players for executing, credit the players for laying it all out there on the floor, but credit Thibodeau for the scheme and getting them to do it night in and night out.
At 18-9, the Bulls are vastly ahead of where they were last season
There are many factors as to why. Derrick Rose has ascended offensively giving them a player who can close out games. Carlos Boozer has given them the second option they need to take pressure off Rose, punish teams for doubling, and initiate offense in the post. Luol Deng and Derrick Rose learned to shoot threes well, answering one of the problems we didn't think the Bulls had answered this season.
However, one of the biggest reasons is coaching, particularly on the defensive end. Tom Thibodeau has put in a plan, preached it in practice, gotten the players to buy in, and has reformed this team into an elite defensive unit. On games where the offense simply doesn't have it, they've been able to buckle down defensively and win the ugly games, and that's one of the marks of a great team.
Tom Thibodeau deserves coach of the year consideration for what he's done with this team, and while he may not win it, the Bulls picked a winner when they hired him this off-season.