I agree with the main posting 100%. The writer nailed everything that Rondo is doing poorly.
Plain and simple, Rondo has been LAZY.
And, don't start with that "conserving energy" nonsense. It doesn't take energy to put yourself in a defensive stance. That alone would improve Rondo's D tremendously.
By far the worst thing Rondo is doing is gambling for steals from behind. He lets his man get past him so he can swat at the ball, but he needs to realize that this gamble is what is leading to the breakdown of the interior defense.
STAY IN FRONT OF YOUR MAN, RONDO!
I mentioned about a week ago that when Bradley returns he'll be guarding the opposing PG, except in cases like Miami, where he'll be on Wade. This will allow Rondo to switch over to guarding SGs, taking him off the ball.