One of the most appealing aspects of Eric Mangini taking over as the 49ers' defensive coordinator was the thought of having Aldon Smith for a full schedule.

That, obviously, is no longer a possibility with Smith being released on Friday after being arrested Thursday night, his fifth arrest since the 49ers made him the No. 7 overall draft pick in 2011.

"A guy like Aldon is not a guy that you just can replace," Mangini said following Sunday's practice.