The Rossoneri received a combined fee of around £52m for the duo last year, but have suffered somewhat of a decline in the 18 months since.
With his former team struggling in ninth place in Serie A, the Brazilian centre-back believes that the club's directors are guilty of errors in judgement.
"If certain things have happened at Milan, then it means mistakes were made," Silva told La Gazzetta dello Sport.
"Was selling me and Zlatan Ibrahimovic one of them? It's difficult to say, you'd have to ask those who are in charge.
"One thing is certain, I always said I didn't want to leave Milan. The Rossoneri got a bargain with me, as they sold me for €42m after spending just €10m. In that sense, I feel that I helped the club."
Milan recovered from a poor start last season to finish third, while Les Parisiens won the Ligue 1 title.