He would kill ball movement and take touches away from the guys in the paint, though. He's also nowhere near the defenders that Battier / TA are.
I do agree that he would kill ball movement. If anything, it's better that they now have Zach as the focal point of the offense 99% of the time.
Rudy was the best isolation defender in the league according to Synergy before he went down, though. He's a sick defender.