Napoli have drawn each of their last four games in the league, including last Friday's clash against league leaders Juventus.
De Sanctis said that Napoli were not good enough against some of the better teams in the league but is confident that they can get back to winning ways against Chievo on Sunday.
"In the last two games we have started to improve our performances," Gazzetta dello Sport quotes De Sanctis as saying. "We have not won since beating Catania, but that is because we came up against some very good teams.
"We hope to beat Chievo but know it will not be easy. We have to keep improving and in the space of five or six games we will know if we are good enough to win the scudetto."
De Sanctis has made 129 appearances for Napoli since joining in the summer of 2009.