Rondo should have Iso's called for him.
Now Holiday aint a scrub defensively, but I bet 10 bucks Rondo could beat him off the dribble. It opens up a world of possibilities on offense.
You usually can't blow by your guy every single possession, so you'd have to live with Rondo pulling up and taking a fadeaway jumper a decent percentage of the time.
I do think they should iso him more often on the perimeter rather than having him isolate in the post.
If you iso him on the perimeter his man can sag off him and help zone up and clog the off the ball action.
Sometimes this works for the defense, sometimes not as it gives Rondo great sight and passing lanes.
I think the C's are using him on the high post to force his man to defend him tight initially to give the play's first action a better chance of working.