San Francisco 49ers defensive coordinator Eric Mangini has conceded that his side cannot replace linebacker Aldon Smith.
The 49ers released the 25-year-old after he was arrested for the fourth time since 2012 last week, this time being detained for driving under the influence.
Mangini has admitted that his side will have their work cut out to fill the void left by the All-Pro for the impending season.
"He's not a guy you can just replace; he's got a unique skill set," Mangini told reporters. "But one of the things we've focused on defensively is building flexibility in terms of what we can play."
Smith recorded 152 tackles, 44 sacks and one interception in his four seasons with the club.
