The defender limped off with a thigh problem during the 1-1 draw with Livorno on Saturday.
"The system always depends on how you approach the game overall and the spirit you play with," said centre-half Cannavaro.
"We tried this tactic for the first time. There were positive and negative aspects. This is just one of those negative spells and we can't seem to win at the moment. What's more, we have conceded in each of our last 10 games.
"It's a shame, as we give our all during the week. I have always said the only solution to all this is hard work.
"We also hope to get a few players back from injury, as there are really too many of them missing now."