I think you're being too harsh on him.
He's been injured, come off a very serious injury, and he's still averaging 13/10/5.
The one thing that p---es me off is his lack of improvement with free throws. Tonight was great but he's just super inconsistent in the shooting department.
I'd say he has more good games than bad games ie: loss to Toronto is very uncommon for him.
To answer your question, well I don't really agree with the sentiment in the question- he's actually very consistent over his career in the things he does best.
This poor guy is playing with four dinosaurs, who when shooting well, are a great compliment to him.
Rondo would be a much more consistent Rondo if Danny decided to use him as one of the main center pieces of a franchise rebuild.
Maybe not the number one option, but the number two spot behind a dominant center or high scoring guard/forward.
Teams like Miami and OKC changed the face of the game for the next 6-8 years, and we need to create a team that counter reacts to that formula, or just simply build a better team at doing the same thing.
The second option is quite viable with Rondo's speed, skill and talent.
That's the dilemma Ainge faces.
Does he rebuild to copy/improve on the Heat/OKC/LA Clippers formula of speed, transition and interior defense.
Or does he go for a Memphis/Lakers system of size, defense and inside out shooting...If Rondo is traded, it's probably the latter.