CHICAGO — After the Bulls sparked controversy in June by trading their franchise star to launch a rebuild, the team’s floor — already below sea level — just kept dropping.In October, only days before the team’s season-opener, forwards Bobby Portis and Nikola Mirotic clashed during practice, with Mirotic suffering a concussion and fractured bones in his face. In November, the Warriors thrashed Chicago by 49 points — without All-Stars Kevin Durant and Draymond Green. Then earlier this month, things seemed to hit a new low. The Bulls, owners of a league-worst 3-20 mark, dropped a 10th-straight game, blowing a 16-point fourth-period lead to the Pacers.Fast forward two weeks, and that same ragtag collection of players who couldn’t buy a win in November is suddenly and mysteriously unbeatable. The Bulls, after blowing out Orlando on Wednesday, are winners of seven straight and own the East’s longest win streak. Only Golden State — 10 in a row — has more. If that seems bizarre … you’re right: Before this, no team in NBA history had ever lost 10 consecutive games (or more) and then rebounded with an immediate win streak of five games or more. Before this Bulls streak, FiveThirtyEight’s NBA projection system1Which, to be fair, doesn’t account for injuries like Mirotic’s. would have given Chicago just a 0.03 percent chance — 3 in 10,000 — of sweeping the seven games it’s won.The turnaround raises two questions for this young club: What, exactly, has changed in such a short amount of time? And are the Bulls at risk of jeopardizing their rebuild and a chance at a good lottery pick by winning too much? The Sixers Still Have Growing Pains To Work Out Related: The Lab Mirotic’s return is the easiest thing to connect to the Bulls’ streak, considering that it began with his first game back. He’s playing unsustainably well — it’s almost impossible to imagine his continuing to be the NBA’s most efficient high-volume post player while shooting 49 percent from the 3-point line. And he’s averaging 35.8 points and 14.1 rebounds per 100 possessions, which puts him among a handful of superstars in the league posting at least 35 and 10.Part of this is opportunity. Mirotic comes off the bench2When Lauri Markkanen is healthy enough to play. but is clearly the No. 1 option when he’s on the floor. That’s a change from the past, when he had to defer to Jimmy Butler, Dwyane Wade or Derrick Rose. But to his credit, Mirotic has made one key change in his game: The 6-foot-10 forward has been more decisive with the ball than in years past. In particular, he has largely shelved a pump fake that often seemed to do the opposite of its intended purpose.According to an analysis published in 2015 by Vantage Sports, Mirotic fired off a shot attempt after using a pump fake more than anyone in the league during the 2014-15 season, yet logged the worst field-goal percentage on those shots among the league’s most frequent pump fakers.3If you broaden the sample by one more year, Mirotic was even worse. He shot just 22 percent from the field after pump fakes over the two-season stretch covering 2014-15 and 2015-16, the worst in the league among players who attempted at least 100 shots after pump fakes in that window. (Unlike Stephen Curry or JJ Redick, who pump-fake their way into cleaner looks by using a side dribble, Mirotic often stood fully stationary and faked his way into a worse shot, which gave defenders extra time to close out on him even further. You can see the difference in the clips below — the first shows a failed pump fake from 2014 and the second, from Wednesday’s game, shows Mirotic shoot in rhythm without any hesitation.)Video Playerhttps://fivethirtyeight.com/wp-content/uploads/2017/12/miroticpumpfake.mp400:0000:0000:00Use Up/Down Arrow keys to increase or decrease volume.Video Playerhttps://fivethirtyeight.com/wp-content/uploads/2017/12/miroticquick.mp400:0000:0000:00Use Up/Down Arrow keys to increase or decrease volume.Pointing solely at Mirotic’s impact would be oversimplifying the genesis of the streak, though. Kris Dunn — acquired in the Butler trade after posting the league’s worst true-shooting percentage among regulars4Who played 15 minutes per night and in at least 65 games. last season — has settled in nicely as the starting point guard after an initial rough patch. He has been getting to the basket regularly — ranking fourth in the NBA during the Bulls’ win streak, with almost 18 drives per game — and finishing more consistently once he gets there.Quietly, backup shooting guard David Nwaba — who also recently returned after being injured — might be having the strongest influence on the team’s winning. He aggressively pushes the ball in transition, arguably one of the bigger shifts in Chicago’s identity. The Bulls have ranked second in pace during this streak, up from 23rd before it. The 24-year-old generates nearly 32 percent of his offense from transition opportunities, the highest rate in the NBA5Among players who’ve checked into at least 15 games and gotten at least two transition possessions per game. and has scored on an impressive 65 percent of those chances. That and his energy on defense explain Nwaba’s presence in eight of the Bulls’ nine most efficient two-man lineups6With at least 100 minutes played. up to this point.“It’s a lot easier for our team to score in transition instead of having to break down a set defense that’s already set up, so I like to run when I can,” said Nwaba, who is on pace to become the first 6-foot-4 or shorter player7Who has played at least 15 games and 20 minutes per contest. in 30 years to shoot 55 percent or better from the field. That mindset is particularly valuable to a points-starved Bulls team that, even after reeling off seven victories in a row, is essentially tied for last in the league in offensive efficiency.These two plays — in which Nwaba catches opposing players off guard by taking an extra dribble or two into the teeth of the transition defense — are typical of how he generates scores for Chicago.Video Playerhttps://fivethirtyeight.com/wp-content/uploads/2017/12/nwaba.mp400:0000:0000:19Use Up/Down Arrow keys to increase or decrease volume.Video Playerhttps://fivethirtyeight.com/wp-content/uploads/2017/12/extradribble.mp400:0000:0000:00Use Up/Down Arrow keys to increase or decrease volume.The defensive improvement has been noteworthy as of late, too, especially since the Bulls have begun playing lineups with four defenders who can all switch their assignments and having their rim protector play pick-and-rolls less aggressively.But no one — well, except maybe Bulls forward Denzel Valentine — expects Chicago to continue playing at this level. (Tonight, the 10-20 Bulls take on LeBron James and the Cavs, who dominated them in a game just before this streak began.) It’s highly unlikely that the Bulls will maintain their Warriors- or Rockets-like shooting from midrange or that opposing teams will continue bricking wide-open threes against them in late-game scenarios.A quick look at the replies under this tweet (highlighting the Bulls’ streak) shows that Chicago fans are worrying about how this stretch of good basketball could hurt the team’s odds of landing a top lottery pick, a concern that still seems a bit premature considering everything that could take place between now and the end of the season.As good as Mirotic has looked, he has had to split playing time with Lauri Markkanen, the team’s promising first-round draft pick.8Also acquired in the Butler deal, although the Bulls traded their own pick to Minnesota as part of the deal. If Mirotic keeps playing anywhere near this level, the Chicago front office would have a nice asset once his contract becomes tradable9On Jan. 15. — a move that would free up more opportunity for Markkanen, who’s far younger and more athletic than Mirotic and has a similar skill set.Beyond that, Bulls coach Fred Hoiberg told me and other reporters Wednesday that Zach LaVine is only two or three weeks away from seeing game action after tearing his ACL last season. His presence in the lineup will alter things considerably, for better or worse, as he knocks off the rust.All of this is simply another way of saying: Yes, the Bulls have been on a historic run the past couple of weeks, but they still have a fair number of flaws to work through. And for those worried about what the win streak means for tanking purposes, the educated guess here is that they’ll still lose plenty of games along the way to stay firmly in the lottery conversation.Check out our latest NBA predictions.