"They let him go and we took him," shrugged Wenger.
Wenger revealed Silvestre was unlikely to feature in Saturday's Barclays Premier League game at Fulham as he regains full match fitness from a muscular strain.
However the Arsenal manager hopes the defender will have a big role within the squad.
"He can play centre-back, he can play left-back and that is an area where we were a bit inexperienced," said Wenger.
"He has a great team attitude and he can help us in the dressing room as well with his maturity."