Since joining from Genoa, Toni has seen Juve beaten twice, shipping seven goals in the process.
He said: "I have seen my teammates angry at the end of the game. They weren't at all downcast.
"There was a desire for redemption in their eyes, to play again as soon as possible and to erase this false step from their memories. It's a good sign.
"We have the entire second half of the season still to play and the results of the last two games show that no one is running away with it and that all the opponents are competitive.
"We knew that it wouldn't be easy against Napoli, but we started well.
"We know that there is a lot of work to do. Now we are thinking about the Coppa Italia, which is an important objective."