This is a bold prediction, and may not come to fruition, but I think the possibility of a serious slip by the Bulls in the 2015-2016 season is higher than people believe. There are several chief reasons for this, but the most important is that their roster really isn't as strong as it might appear on paper.
Simply put, almost all of the Bulls' key players are old or very injury prone. This is usually not a good sign for obvious reasons. Derrick Rose's knee issues are infamous, and while he played 51 mostly healthy games last year, he was noticeably better on days with more rest. Another year removed from surgery could improve his play (he was awful efficiency wise last year and has always turned the ball over too much), but it might not either. Overall, I would say at this point he is no better than an average starting PG in the NBA.
The rest of their roster has similar issues. Taj Gibson has missed around 18 games in three of the past four seasons, and he too had a down year in 2015. He could be more injury free this season, but that looks unlikely, and he is also 30, the age when players start to decline in play. Pau Gasol had a bounce back campaign last year after several injury plagued and mediocre seasons in Los Angeles, but he is 35 and has many additional miles from international play and deep playoff runs with the Lakers. In all likelihood, he too will not reach his 2015 statistics, which were already overrated because his defense has become so poor. Joakim Noah was awful last year while struggling with foot issues- his shooting fell off a cliff, he stopped getting to the line, and his defense went from incredible to average- and while he is the most likely candidate to regress to his career mean, he is 30 as well, and foot problems are notoriously tough to cure.
Outside of Jimmy Butler, who had a major breakout and probably won't lose too many of his statistical gains, the remainder of the rotation is old and declining as well. Kirk Hinrich is 34 and can't do anything but occasionally hit 3s and pass the ball around the perimeter. Aaron Brooks is 30, inconsistent, atrocious defensively, and relies heavily on his quickness to get to the rim. Mike Dunleavy is still a solid rotation player due to his shooting ability, but his defense has slipped as well.
Obviously not all is doom and gloom. Butler is one of the best wings in the NBA, a tremendous two way player who could still improve. Nikola Mirotic had a very solid rookie season, though I think he got overrated by the end of the year. His outside shooting was poor (31.6% from distance), his overall field goal percentage was worse (40.5%, awful for a wing/big), and he needs a lot of work on defense. Now, the shooting and defense will probably improve, but sometimes the sophomore year in the NBA is harder than the rookie season, and Mirotic isn't a lock to breakout. The rest of their youth is largely untested: Bobby Portis is a rookie, Doug McDermott played only 320 minutes as a rookie, and Tony Snell faded in and out of ex coach Thibodeau's rotation. Speaking of.......
The biggest change for the Bulls this year will be the substitution of former Iowa State coach Fred Hoiberg for the five year tenured taskmaster Thibodeau, who lost the support of the front office and some of his players. Thibodeau had his flaws: an awful tendency to overplay key players leading to injuries, subpar rotations, and a largely inflexible and out of date offense. Nonetheless, he is one of the best defensive coaches in the league, and his ability to make his teams play tough defense and compete as a total package is quite probably second to none. The injuries, offense, and the possibility that his defensive system was a little out of date pushed him out.
Hoiberg is supposed to be a good coach, and is known for his free flowing and exciting offense- a huge contrast in styles. However, it is almost always a very tough transition to move from coaching the college game to the NBA, and Hoiberg has a lot of personalities to juggle right out of the gate. The Bulls' offense will probably be better, and possibly a lot better, but their defense could suffer severely, especially if Noah fails to recover to his form from 2012-2014.
The final issue lying in the way of the Bull's being a lock for a playoff spot, much less home court advantage, is that the East is finally starting to improve. The only true tanking team is the 76ers, and while several other teams are not likely to be good, there could be as many as 11 solid teams in the East this year (counting the Bulls). The Pacers will have Paul George back, and while they lost their starting frontcourt, they finally added some offensive firepower with Monta Ellis. The Hornets, Magic, and Pistons are unlikely playoff teams, but all should be improved and tough to beat at home. The Celtics don't have as much talent as the Bulls, but Brad Stevens is a wizard at head coach, and who knows what he might be able to cook up. The Wizards, Bucks, Raptors, and Hawks are all still likely to at least be good, and the Heat with Chris Bosh and Josh McRoberts could be a lot better than last year.
If the Bulls have any combination of problems with injuries, older players declining, and Hoiberg struggling in his rookie season, I think they will fall out of the playoffs.
My Eastern Conference Playoff Bracket
2. Miami Heat
3. Washington Wizards
4. Atlanta Hawks
5. Toronto Raptors
6. Milwaukee Bucks
7. Boston Celtics
8. Indiana Pacers