I agree with you that Jet and Pierce's cold shooting has been a big detriment, and I also agree with you that the lack of offensive rebounding is part of Doc's system, so yes, some blame goes to Jet and Pierce, and some goes to Doc.
Doc deserves another measure of blame, as well, for not utilizing the strengths (driving, slashing, pick and roll) of the guys Danny brought in this season. He also deserves blame for decreeing that Rondo have the ball 90% of the time.
And yes, Rondo does drive a fair amount, but he's not a mad dog about it, you know? I mean, he's fast, and has a great handle, and is also really good at getting off shots at crazy angles that are hard to block, but he doesn't go in there enough for me—and I think it directly relates to his poor free-throw shooting. So maybe he isn't "afraid" of contact, per se, but he definitely shows a hesitancy at times that probably has something to do with free-throw shooting.
Yes, our offense is usually one of the most efficient in terms of FG%, and it's usually at or near the top in assists, but it also regularly takes a low number of shots, which somewhat negates the high shooting percentage, and it also goes stagnant a lot. Why? Because if the jumpers aren't falling, there's no Plan B, no adjustments, no variety with which to kickstart our offense and at the same time throw off the defense.