I think they are the most dangerous team in the East. Philly was that club but their recent winning streak has them as the "hot new upstart that can unseat the Cavs" from parts of the NBA punditry/blogosphere/Twitteratti.
Get Smart back and this team can torment anyone between their defense, ball movement and scheming. Would you want to face Boston in a close game with a few seconds left? They routinely get stops and somehow, they find an array of open men who then hit shots (Horford, Mook, Brown, Tatum, T-Rozay...). At this point, their lack of a focal point scorer is more of a feature than a bug. And while I expect Stevens rotations to be a bit shorter - they may reach their "nadir" today - he is essentially unlimited in terms of whom he uses and how he uses given that he really only has one "star" left in Horford. If he needs to adjust on the fly to counter something, he can pretty much pull anyone off the floor and it will generate little in the way of media controversy or, more importantly, bruised star egos.
In short, without Iriving, this team will have a hard time winning any round. However they just might get to the ECF and take that to the limit as well given the make-up of the other teams.