It is too early to make such comment in my opinion. Because there are 22 more games to be played for Napoli. Everything can change significantly in this time period. Mazzarri isn't a very successful manager considering his whole career so I wouldn't be so sure about him already. He doesn't have a much different career than Rudi Garcia in the end.
This win over Cagliari was good for Napoli. This would surely improve their morale to play better in next games. But we need to see some consistency from them in the future to be able to trust them more for betting on them as well. For now I will continue to avoid betting on them.

Staying Consistent shouldn't be too much of a big deal for Napoli. They have to play again like they did last season even of that'll be difficult to see. They did yesterday though, I saw togetherness amongst the players and the first half was also filled with chances and entertainment.
Asides them next game against As Roma, the next four games in the league won't be difficult, only if they avoid getting Injured and stay focused. A little bit of fatigue could come up when they begin the second phase of the Champions League round of sixteen. Goal ans assist for Victor Oshime, he's goal was great but have you seen his assist for Khivicha Kvaratskhelia? That was a great game for them.
I have seen Osimhen's incredible assist, yeah.

He told us with that amazing assist that he was ready to rock again. Osimhen's best performance is really needed for Napoli to recover quicker. They need to get better in big games as well in time. They can do this by having a bigger scoring productivity from now on.
That Roma game is really going to be challenging for Napoli next time. It is an away game and Roma would definitely like to win this game to have a morale boost and put an end to their bad streak as well. This is another big test for Mazzarri so let's see what he will do.