Santon has been linked with a return to Italy this month.
"I know that Santon was a promising youngster and I don't think he has lost those qualities," Tassotti told Sky Sport Italia.
"It would be good for Italian football to have him back in the country. Mattia De Sciglio has always been comfortable on his right or his left foot. He has grown a great deal and is an important player for our squad."