Is Rondo slowing the pace or just playing at the same speed as the team? Are people open and calling for the ball while Rondo dribbles it looking for a "more perfect" pass?
I think Rondo is slowing the pace but as you suggest, it is a team game and not entirely any one person's fault. As the PG though, Rondo is highly impactful in this aspect. His focus should be on first getting the ball up the court to the point of attack as quickly as possible, then he needs to focus on just making the next pass, not always the last pass (which in many cases turns out to be the only pass).
I think there is room for improvement in both areas but lately, I think the second is the bigger issue. I think our set offense works best when everyone touches the ball and assists are distributed and come after 2 or 3 passes, not just one pass. We get bogged down when Rondo is dribbling around (actually he is often just dribbling in place) as the other 4 are making and cutting off screens. Instead of passing for the sake of ball movement, he seems to be waiting to pass to someone who will be able to take a shot.
Successive passes (along with dribble penetration) force defensive responses that utimately lead to opportinities. I guess it could be all Doc's fault for not calling the right plays but since he is clearly not happy with it, I doubt this is the case. Doc has said he doesn't want players taking "hero shots" and I think Rondo is trying to make what amount to hero passes. I am pretty sure Doc doesn't want that either.