Rondo's passing up shots for the assist stat has been well noted. But it should also be noted that he's been left wide open far more than the other top PGs. Also, it has been my observation that he actually shoots better when he doesn't have that much time to think about it (such as with FTs).
So the idea jumper situation for him may be to be left wide open, because the defense is busy guarding the greater offensive threats--and then be tossed the ball in the last seconds of the shot clock, so he just has to shoot.
And no, I have no stats at all to back up my conjecture built on conjecture.
Also, to be fair to him, 1) he has improved his jumper in recent years, and 2) he's always been good at delivering a high personal FG%, which is good for the team.