It's realistic to expect a couple bumps in the road. The team is not playing well, that much is obvious, but seriously it's a pretty difficult thing to expect the team to be playing 100% full tilt full time. Celtic is right too, this team is getting the absolute best shot from most of their opponents (with the noted exception of Washington, who might not even have a best shot anymore).
However, there are a few pressing issues I've notice. First, Rondo's emergence has been a blessing and a curse in that now teams have discovered the best way to shut down the Celtics has been to focus their defensive effort first on Rondo penetrating. The Knicks did it decently well at times, and the Lakers did it on Christmas. As Rondo was under the radar last year, teams wouldn't gameplan for him the way they would Paul, Kevin, or Ray. Now all this "Big Four" talk has lead teams to include him in their preparations.
Also, the backups at every position have had rough starts to the year. The team NEEDS to get bigger IMO. Big Baby has not impressed me thus far this year at all, taking quite a few jumpers and not shooting well (37% on the year) and only contributing under 3 rebs per game. No real organization with the ball distribution either... TA shoots too many threes at a .150 clip. Eddie House has shot okay from the floor (39%, with 36% from distance), but has been real streaky this year and will continue to shoot at all times. It seems like he's trying to make up for the loss of Posey's shooting all by himself. Scal is Scal, and you can say what you want but he shouldn't be getting meaningful minutes on a championship team. I also don't like Leon Powe's 4 rebounds per game... I would like to see a little more then that. The whole bench combined is averaging 12.1 RPG.
Bench ranks according to 82games.com
Reb- 22nd
PPG- 16th
Assists (here's a big one)- tied at 26th, second to last at 4.3 APG only .1 above last place New Orleans
Troubling trends here... Not jumping ship here yet, but there are moves to be made to improve the bench, and it might be time to make them.