Ferrara started the game with both Diego and Alessandro del Piero on the pitch, but the pair struggled to make an impact in the Champions League defeat.
La Stampa says Diego didn't mince words at the final whistle, barking: "Something is wrong and it's up to Ferrara to find out what."
Ferrara insists their general play on the night was good.
"We suffered a great deal with free-kicks and corners, not so much our level of play. However they have certainly deserved their victory," said the coach.
"I'm not happy with the team, not just Alex. Nearly all have had great difficulty."