I never said you couldn't win a title, or multiple titles without a great point guard, so the point should be clear Nick, that I am not speaking in absolutes here. You most certainly "can" win titles without a great point guard.
Also, I might hestiate labeling Derek Fisher as one of the worst point guards in the league, the guy has what, 5 rings playing at that position? We might not want to underestimate him...like Rondo did by leaving Fish wide open at the three point line in game seven with the score 64-61 to go and try and help one of the best all time post defenders in NBA history ( Garnett) on Pau Gasol. Just "slightly stupid" on Rondo's behalf. You don't leave Derek Fisher alone at the three, ever, and especially in a crucial game where he has a chance to make a "huge play". He will kill you. It was a game changing play, the resulting Fisher three that tied it 64-64 and from my perspective sealed the champiionship for the Lakers, it was downhill to the title for them after Fisher's three pointer.
I wouldn't underestimate the guy.
Maybe a different way to make my point is.
The Heat will be very good as constituted. They'd be devastating with Rondo leading the break with Wade and LeBron on the wings.
The Bulls teams were great. How much better wouldn they have been with Chris Paul as well?
The 80's Celtics were great with DJ. How much better wouldn they ahve been with Steve Nash leading the break?
How much better would the current Lakers be with Rondo?
I would argue it isn't just the number of assists a guy gets but how he controls the pace of the game and how much better he makes everyone around him.