When the Chicago Bulls have had to play without Derrick Rose in past years, they've been able to rely on one of the NBA's best defenses. Chicago has ranked in the league's top five defensively in all four seasons since it hired Tom Thibodeau in 2010 and led the NBA in defensive rating twice in that span. With Rose limited to 10 games a season ago, the Bulls ranked second, which helped center Joakim Noah earn Defensive Player of the Year honors.
While going 3-4 since Rose was sidelined with a torn medial meniscus that required arthroscopic surgery in his right knee, Chicago hasn't been able to summon that same defensive effort. In fact, after it surrendered 116 points to the San Antonio Spurs on Sunday, the team's defensive rating in Rose's absence ranks 24th in the NBA, per NBA.com.
Although the Bulls have also played the past four games without their premier wing defender, Jimmy Butler, this defensive drop-off isn't new. Over the course of the season, Chicago ranks 13th in the league in defensive rating. Where has the Bulls' trademark defense gone?
What's gone wrong
First, let's figure out where Chicago's defense has broken down. That requires starting with something interesting: areas where the Bulls are just as good as ever defensively, which include defense of opponents' shots, the most important element of defense. Chicago ranks fourth in opponent effective field goal percentage (.477), which accounts for the additional value of 3s. The Bulls also rank in the top five in terms of keeping opponents off the free throw line.
That leaves the other half of Dean Oliver's four factors as the culprits. Chicago ranks just 17th in defensive rebound percentage, down from 11th a season ago. The Bulls are worse yet at forcing turnovers; no team in the league has created fewer on a per-play basis, which is stunning, given that Chicago had an above-average forced turnover rate a season ago (11th).
Pau problems
There's no denying Pau Gasol has been rejuvenated since signing with the Bulls as a free agent this past summer. Gasol is averaging 18.3 points and a career-high 12.1 rebounds per game, and he was voted an Eastern Conference All-Star starter. However, many of Chicago's defensive issues can be tied to Gasol's presence.
With the Spaniard on the bench, the Bulls are forcing turnovers on 13 percent of opponents' plays, which would rank 20th. When Gasol plays, that rate drops to 10.9 percent of opponents' plays, which is not only the lowest mark in the league but would also be the third-lowest for any NBA team since turnovers have been recorded. The worst mark, not coincidentally, belongs to the 2011-12 Los Angeles Lakers, who also started Gasol next to a traditional big man (Andrew Bynum).
As fellow ESPN Insider Amin Elhassan pointed out, Gasol's lack of mobility is a hindrance on defense.
"He's relatively immobile laterally," Elhassan said. "Pau is more comfortable defensively when the action is funneled toward him and not when he had to move and rotate over."
Advanced stats also take the air out of Gasol's gaudy rebounding numbers. Chicago's defensive rebound percentage is far better with Gasol on the bench (76 percent, seventh in the league) than on the court (73.5, tied for 22nd).
Noah's physical ailments early in the season exacerbated the issue. Noah underwent knee surgery in May and admitted to the Chicago Tribune in November that the procedure was "more than a scope." On top of that, Noah has battled a series of ankle sprains. As a result, it was difficult for the reigning DPOY to chase power forwards playing alongside Gasol.
The Gasol-Noah lineup has contributed to another surprising Bulls weakness: transition defense. Chicago is giving up 15.5 fast-break points per 48 minutes with Gasol and Noah on the court together, which ranks as the league's second-highest mark. With Gasol on the bench, the Bulls are average in fast-break points allowed per 48 minutes (12.7), similar to their performance in past seasons.
Rose effect
Before Rose's injury, there were signs Chicago was turning the corner defensively, as Noah and the rest of the team got healthy. Between Jan. 22 and Feb. 23, the Bulls' defensive rating was third in the league, and his final game before surgery against Milwaukee was the team's best defensive performance of the season. The improved defense fueled Chicago's rise up the standings.
The past seven games have revealed the thin margins on which the Bulls' defensive success is built. With opponents committing few turnovers, Chicago has to be elite in terms of forcing misses and avoiding fouls. Without Rose, that hasn't been doable. Opponents have made 2-pointers at an above-average, 48.8 percent rate and attempted 24.4 free throws per game, up from 18.5 over the previous month.
Unlike in past seasons, Rose is coming back, which gives the Bulls the opportunity to get back to the level at which they were defending before his injury. But their inability to lock down in Rose's absence might prove costly in terms of playoff seeding.
News and notes
• Chicago's opponent Monday, the Memphis Grizzlies, are one of the two teams with a superior defensive rating the month before Rose's injury. In fact, Memphis had the league's best defensive rating in that span and allowed 4.8 fewer points per 100 possessions than anyone else. Without the same kind of injury-related explanation, Memphis too has dropped off since the All-Star break. Over their past nine games, the Grizzlies' defensive rating ranks 15th.
With Memphis' attack struggling after a fast start (the Grizzlies were better on offense than defense, prior to the Jeff Green trade), the team needs to get back on track defensively. Although Memphis has gone 5-4 since the break, the team has been outscored by 2.8 points per game. The Grizzlies' overall point differential (plus-3.7 PPG) now ranks sixth in the Western Conference, ahead of just two other playoff teams (the Houston Rockets at plus-3.6 and the Oklahoma City Thunder at plus-2.7).
• The battle for the last two playoff spots in the Eastern Conference seems to be clearing up. With the Charlotte Hornets beating the Detroit Pistons on Sunday and the Boston Celtics and Brooklyn Nets losing, there is now a 2.5-game gap between the teams tied for eighth (the Indiana Pacers and Miami Heat) and the Celtics and Nets, tied for 10th.
The Pacers, currently riding a five-game win streak and a league-best 7-1 record since the All-Star break, look like a safe bet to finish seventh.
Bosh
Dragic
That would leave Miami and Charlotte competing for one spot. Charlotte has also won five in a row, a level of consistency the Heat -- 3-3 since trading for Goran Dragic and losing Chris Bosh to a season-ending blood clot -- have been unable to achieve.
• The other story coming out of Sunday's games was the resurgent Spurs offense led by a healthy Tony Parker. After averaging just 105 points per 100 possessions during the "rodeo road trip," San Antonio has posted a 120.8 offensive rating the past three games. Adjusted for opposition, the past two -- Friday's 120-111 win over the Denver Nuggets and Sunday's win over the Bulls -- have been the Spurs' two best offensive outings since Jan. 3.
The most obvious difference has been Parker. Battling the nagging effects of a hamstring injury, he shot just 35.5 percent from the field on the road trip and had a three-game stretch in which he combined for nine points on 3-of-21 shooting. Over his past three games, Parker has made 31 of 48 shots (64.6 percent) and scored 75 points -- his best three-game total of 2014-15. Remarkably, San Antonio has emerged from the 4-5 road trip just a half-game back of the Los Angeles Clippers for fifth in the West and still within striking distance (2.5 games) of the Portland Trail Blazers for home court in the opening round.
• Weekly top five: Best current, undrafted players:
5. Jeremy Lin
4. Jose Calderon
3. Robert Covington
2. Timofey Mozgov
1. Wesley Matthews
Honorable mentions: J.J. Barea, Anthony Morrow, Anthony Tolliver
Follow Kevin Pelton on Twitter @kpelton.