While it is still too early to panic, there is also plenty of time to worry. There are plenty of reasons to worry as well. I'm not even talking about the normal age and tired legs issues either. This is beyond that. These are issues that can and should be worked on soon. Lets right to the list, shall we?
Defense:
This is a really odd item to put in a list of Celtics weaknesses, (especially when we are near the top of the league in points allowed and point differential) but hear me out. This team still locks down teams for stretches of games, but there have been far too many stretches where the defense disappears or looks disinterested. I know that teams make runs but the Celtics of the larger part of the last two years never let those runs last that long. The lack of consistency is what is killing this team right now.
Consistency is absolutely mandatory for a defensive team. Guys have to know, beyond the shadow of a doubt, that help defense is going to be in the right spot. If they don't know that, they may gamble or hedge or make bad decisions trying to compensate for the fact that the other guys won't be there to stop their man. Which sometimes works but usually gives up easy baskets.
Frankly I care little about the offense. If the defense is consistent, we would win these types of games.
Ball Movement/Shot Selection:
With that said, the offense isn't totally off the hook. First of all, lets get this out of the way right now. Maybe Sheed is taking too many 3's, but we all should have known that coming into this and the Celtics certainly did when they signed him to a 3 year deal. Screaming at the TV for Sheed to get in the paint is only going to get you a prescription for tea and honey. He's not changing his spots. I'm also not going to kill him for the 3's that he took against the Magic. They were good, open shots for the most part. Over the course of the season, he's going to make his fair share and there will be a time when he'll win a game or two with those types of shots.
With all that said, I'd like to see those shots set up by penetration a little bit more. Rondo is the master at this and when he's off his game it really throws a wrench in the works. It doesn't have to be him though. When Pierce is attacking the basket, he forces the defense to collapse on him, opening up kickouts to Ray, Eddie, and yes Sheed. When we've got Eddie or Paul holding the ball at the top of the key and waiting, waiting, watching Ray run through screens, holding off the defender with a forearm, feet planted, with a confused look, ...well, that's not good ball movement.
Perk is the closest thing we have to a traditional low post threat, so other than feeding KG and Sheed on the block for fallaway jumpers, we have to drive to collapse the defense. Once that happens, then you can bomb away and make them pay.
Rebounding:
The Celtics are dead last in rebounds so far this year. This puzzles me. Theres no reason why Perkins shouldn't be pulling down his fair share of rebounds. KG has been otherworldly dominant in the past on the boards. Both are at just over 7 boards a game. You don't really think of your point guard much when talking about rebounds, but Rondo has been huge on the glass in recent years and his numbers are down this year. Shelden has been the one bright spot but his contributions have been limited and might be limited even more when Big Baby returns (and Baby has never been a great rebounder despite his girth).
The Good News:
I'm sure there are some more reasons to worry, but there are also a few silver linings here. This is still the same group of guys that beat the Cavs and rolled out to a 6-0 start. They can put it together and there's a better than good chance that in time they will. Also, the majority of issues listed above can be fixed with a little bit of coaching and extra effort. You can't turn back the clock on the age of the vets, but you can help them see the game a little better and motivate the whole team to give a consistent effort night in and night out. I'd rather go through these struggles now and fix them as the season progresses than to fall apart at the end, but the key is to fix them before they become habit.
So there's time enough to get better, but I'd like to see it start happening sooner rather than later.