What's Wrong With the Chicago Bulls?

The Bulls have not been the Bulls we've come to know and love over the past few years.

Yeah, we know Derrick Rose is yet to reach peak Rose form once again. And I'm not sure if anyone knows if and when that's going to happen. But we do know one thing. Over the past four years, Chicago has been one of the premier defensive teams in the league.

Since Tom Thibodeau took over as head coach in 2010, the Bulls have been built around defense. In the last four seasons, the Bulls have posted an average defensive rating of 100.5 points per 100 possessions -- an average of -5.5 relative to the rest of the league (meaning the average defensive rating throughout those years would've been roughly 106). That's what we call a defensive culture.

But now, in 2015, the Bulls have a much-improved offense. They have increased their offensive rating from just a year ago (102.5) by 5.6 points per possession. Their rating of 108.1 is tied for 10th in the league. That's definitely good. But, as the Bulls have improved on offense, they've done the opposite on the defensive end of the floor. Today, the Bulls have a defensive rating of 105.2. That's 12th in the league and nearly 5 points worse than their average over the previous four seasons. So, what do the Bulls, and Coach Thibs, have to do to get back to their defensive ways and win some games?

Problems

Injuries

For starters, the Bulls have ankle problems. Forward Mike Dunleavy is still out with a right ankle injury he suffered on New Year's Day, and he hasn't been able to run without pain since. Then, on Wednesday, in a game against Washington, Joakim Noah suffered a sprained ankle and exited the game. The extent of the injury isn't known yet, but it's worth noting that it's the same ankle he's had problems with earlier this season. Clearly, this will influence lineups going forward, but we're going to operate based on the assumption that both will be back in the near future.

Defensive Issues

This table below shows how many games and minutes per game each of these lineups has played together so far this season. It also shows a few different defensive statistics for that lineup. But most importantly, it shows the net rating (offensive rating-defensive rating) for each lineup during its time on the floor, which shows us how many points that lineup would gain on its opponent during the stretch of 100 possessions.

As you can see, the Bulls haven't been too good defensively this year. Well, that statement is partly true and partly false. The two main starting lineups (the top two lineups in the chart) for the Bulls this year haven't done well defensively. Those two lineups have logged a total of 395 minutes so far this season. So, it's no wonder the Bulls defensive rating as a team is 105.2 then. However, some lineups have defended very well together in limited time on the floor. The bottom three lineups in the chart above have logged just a total of 143 minutes combined this year. There's the problem.

The Bulls' "reserve" lineups have been much better defensively and as a whole than the two "starting" lineups. With guys like Kirk Hinrich, Taj Gibson and Nikola Mirotic on the floor with a few of the starters, the Bulls have actually thrived defensively. Hinrich's inclusion comes as a surprise since he's only managed a defensive rating of 109.

As for Gibson, he's also struggled a little defensively this year with a rating of 105, but maybe it's just the rotations. Gibson possesses a career defensive rating of 100 and has been a really solid defender for the Bulls in recent years. Mirotic, on the other hand, has defended well in 2014-15. He's earned a defensive rating of 101 while playing mostly the power forward position with the exception of a small experiment at small forward. With all that being said, what should the Bulls do to improve?

Possible Fixes

Generally, after looking at the numbers, the answer's clear: change up the lineups. But, what in particular could Coach Thibs change in order for the Bulls to improve on the defensive end of the floor, and get over their recent struggles?

For one, Thibs should start the last lineup above, consisting of Rose, Hinrich, Butler, Gibson, and Gasol. Yes, of the three non-starter lineups that one has the worst defensive rating. However, they've only logged 4.7 minutes per game in 11 games so far this year. They could very much improve with time together. Rose definitely needs to step up his game. He's posted a lackluster rating of 109 so far this season. But I'd expect the defensive versatility of both Butler and Gibson to help him out. And it doesn't hurt having a net rating of 22.7. With Rose, Butler, Gasol and Gibson on the floor at the same time, there's a lot of offensive versatility to go around. And when Dunleavy returns, Thibs could insert Dunleavy and his three-point prowess in place of Hinrich.

But what about Noah? Well, when he's healthy, I would suggest Noah slide to the bench and come on alongside Gibson. They've played very well together pre-Pau Gasol. It would be nice to see them log some minutes together before Thibs brings on Mirotic to give Gibson a break. And when it's time to bring back Pau, the two international talents could continue their great play together. With a net rating of 38.0, there's no reason the two shouldn't play more together.

From the information above, this looks like the ideal rotation, especially for the front court. But, as long as Thibodeau does some tinkering with his lineups, he should see better results. With Dunleavy and Noah out for now, he's going to get the opportunity to see how those lineups might shake out too. It'll be interesting to see what changes he makes, if any, and how the Bulls perform in the next ten games or so. If Thibs does in fact change up the lineups, look for the Bulls to get back on track and be championship contenders (they have a 6.9% chance of winning the championship, according to our metrics) by regular season's end.