Silva turned to former-club Watford to make the 21-year-old his first signing in a £40m deal in late July.
"I can speak to you about what happened one year ago when we took Jordan Pickford and everyone was talking about it at that moment," the Portuguese manager said ahead of the trip to Premier League newcomers Wolves.
"Now no one is talking about his value. The value the club paid to take him here is normal in football. The market now is really difficult.
"If the player will perform well and do the best to achieve our goals at the end no one will speak about the price."