I'm usually looking at Rondo. If Rondo was playing aggressive, they'd have no need to play through Pierce. So even though Pierce might not be as effective as he has been in the past to finish up games, it all starts with Rondo and how he's running our team. Just check all the games and the various points during which Rondo is aggressive and when he's not, and you'll see a pattern of when we play well and when we struggle.
But does Rondo decide on his own not to be aggressive or does Doc or Paul decide that they should run the offense through Paul more? I've never understood the thinking that Rondo decides on his own that he'd rather, for instance, give the ball to Paul and stand in the corner than run the offense. I think it's more likely that Paul or Doc makes that decision. I do think that he starts the game trying to get his team involved instead of trying to take over the offense, though.
It's a mixture, but Doc has NEVER told Rondo to not be aggressive. Just the opposite. I would think that if Rondo were running the offense as it should, as he does when he's aggressive... opening tons of opportunities for our various players in the court, that Doc wouldn't go away from it. It just so happens that Rondo has this problem when he stops being aggressive enough, stops pushing the ball (as it has been asked of him countless times) and it makes our offense run that much worse. So they go through Pierce instead. Now if Rondo is doing as he should, and we go away from it, then that's another thing entirely... but before we start playing the "go to Pierce and clear out" game and the likes, Rondo for the most part has removed his feet from the accelerator.
Let me just say this, I think Rondo has been overall quite fantastic this season, but it's these little things that are quite lethal when he's not doing it correctly... or consistently.
There's a ton of blame to go around, but as I've said in the past countless times, it all starts with how Rondo is running the offense, and if he's pushing the ball and being aggressive. If at the very least he's doing the last two, then we should be good to go as long as he's sharing the ball while doing so.