They're having Rondo handle the ball less, both by playing him less and having him do less when he's on the court.
That greatly changes the C's offense, for the worse, because Rondo is the C's best offensive player when he's right.
How is Rondo the C's best offensive player?
?
He's the Celtics best option when it comes to creating a good shot. Usually that means someone else is shooting it, or he's taking a shot at the rim.
As Rondo goes, so does our offense because of this.