Sunday, December 20, 2015

The Bulls Offense in Four Charts

25 games into the season, the Chicago Bulls have yet to distinguish themselves from the rest of the Eastern Conference morass. At 15-10, they sit tied for fourth in the standings, but have only the ninth-best point differential in the East. The stingy defense, ranked second in efficiency, has been a pleasant, yet unexpected, surprise. More surprising though, is an offense that has dropped from 10th last season all the way down to 27th this season, with almost the exact same personnel.



To see where the offense is struggling, it's helpful to look at the Four Factors. The chart below shows the Bulls' offensive indicators compared to last season:

Year eFG%TOV%OREB%FTA%
2014-15 48.912.927.030.4
2015-16 46.7 12.823.525.6
Difference -2.2 0.1-3.5-4.8
Courtesy of Basketball-Reference.com

While the Bulls remain one of the better teams at taking care of the ball, they have had significant drops in the other three factors. What's behind each of these declines?

Shooting
The league average effective field goal percentage is around 49.5%, so even last season the Bulls were below average, but not by much. This season, only the Grizzlies and Lakers are worse. One explanation is that their shot distribution has changed:

Year 0-3 ft.3-10 ft.10-16 ft.16+ ft. 3PA
2014-15 .308.156.099.163.269
2015-16 .286.164.115.187.248
Difference-.022.008.016.024-.021
Courtesy of Basketball-Reference.com

The most efficient shots are either near the basket or behind the three point arc, but Hoiberg's offense is exchanging those shots for more in the midrange. Last season, nearly 58% of the Bulls shot attempts were either layups or threes, about 2% better than league average. This season, only 53% of their shot attempts come in those areas, 4% worse than league average. This is not a good change. 

Even when the Bulls do get layups, they are finishing them at a league-worst 55.2%, down from 59% last year. (league average is around 62%). The biggest culprits are Derrick Rose and Joakim Noah, who combined are shooting 47.8% inside three feet. 

Free Throws
With a decrease in the number of shots near the basket, it's no surprise that the Bulls also have had a significant dip in free throw attempts. They were one of the very best teams a year ago at getting to the line, and this season they're in the bottom ten. Here's a look at the free throw rates of the returning rotation players:


Player2014-152015-16Difference
Brooks.213.179-.034
Butler.508.483-.025
Gasol.317.271-.036
Gibson.364.324-.040
Mirotic.455.260-.195
Noah.407.394-.013
Rose.224.169-.055
Snell.148.113-.035
Courtesy of Basketball-Reference.com

Every single rotation player has seen their FT rate decrease from last season, suggesting it's probably a byproduct of the system. Part of that could be the increased pace: the Bulls are shooting much earlier in the shot clock than they did last season. This seems to be affecting Nikola Mirotic especially. Of particular concern is Rose's dip, who now sports the free throw rate of a spot-up shooter, not someone whose best skill is getting to the basket.

Offensive Rebounding
Offensive rebounding is another area where the Bulls went from top five in the league to bottom ten. Once Hoiberg decided to start Mirotic in Noah's place, this shouldn't have been a total surprise. Take a look at how the Bulls have done on the offensive glass with each big-man combo (keep in mind league average is around 24%):


PairMinutesTeam OREB%
Gasol/Mirotic36917.6
Gibson/Noah26228.2
Gasol/Gibson24123.4
Mirotic/Noah15827.0
Gasol/Noah12128.2
Courtesy of NBA.com/stats


The Bulls' offensive rebound rate when Gasol and Mirotic share the floor is not only the worst in the league, but worst in league history. Give credit to Hoiberg for finally breaking those two up. This also shows that despite not being a threat to score, Noah may not be a complete zero on offense, and gives more evidence that a Mirotic/Noah pairing could work well on both ends.


If last season was any indication, the Bulls do have the personnel to have a good, if not great offense. However, we are far enough into the season that these numbers are significant indicators. Coach Hoiberg has not proved that he can unlock the offense potential in Chicago, but we will see what adjustments he will make to change that.

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