It is the same problem the Bulls will have until they sack Tibs or he radically changes his coaching style. They play at 100% for 48 minutes all regular season long. When the playoffs come, or the last 5 minutes of a playoff game come, they have no next level to take it to. You get what you get from them.
Compare that to any number of teams that play knowing they have a long season and need their legs down the road. They can, and do, step up and play at another level.
The Bulls playing in fifth gear can oftentimes beat other teams playing in fourth gear. That happened all last season and all this season. Once the other team (not just the Heat, other upper level teams) also go into fifth gear the Bulls weaknesses become apparent.
Tibs pushes his guys too hard, and they give off the appearance that they are better than they really are. This keeps the GM complacent as the look like they have everything they need to make a championship run. They don't.
The sooner they realize that playing in fifth gear all the time is not helping them, the better off they will be. If they weren't playing so well (so hard) then they probably would have pulled the trigger on Dwight Howard. Then they would likely be front runners for the championship. Instead they are bringing a collection of role players and one superstar (who happens to be oft injured now, ankle, back, groin, etc) who has an insurmountable weakness that no coaching or refinement of his game can overcome, his height. They will get shut down in the playoffs they way they did last year, and that will continue until they shake up their roster and their coaching (either style or the actual coach).