This is supposed to be "Rondo's Team" this year. Unfortunately, it is not an especially good team but when you are supposed to be "the guy" on the team, you are going to get more credit than you deserve for the wins and more blame for the losses. That is the situation that Rondo is in.
This is his first chance to be the clear leader and best player on a team and he is not performing very well relative to the standards of that type of role on the team. He is pretty much the same Rondo that he has always been, highly talented but flawed, competitive but mercurial, and a few other contradictory things like that which if I was a better writer, I could probably articulate.
Yes, if you put better players around Rondo, the team would probably win more but I think Rondo would still be Rondo. He is a fine $13M per year PG; to me, that is about where he should be paid relative to other comparable PGs around the league. If that was his role on the team, he would be fine but somehow the expectation got a little out of control.