Im sure that none underestimated napoli at this moment. Napoli has proven its quality through domestic league. However, napoli may face a problem once it will be losing some important players and that will be forcing napoli to think the best rotation and im sure that will give a very big impact to the performance from the napoli. napoli is very consistent at this moment but i didn't think that if the change of players will not give any impact to the performance from napoli.
Indeed, in the early matches, maybe Napoli was not considered, but over time and seeing how they have performed so far, Napoli really deserves to be considered and they are excellent. I'm sure that right now there are no clubs that underestimate Napoli's strength, maybe even several clubs have targeted Napoli players. So far, Napoli's results have been very consistent and keep getting better. Spalletti is truly extraordinary in devising tactics so that they are always able to attack their opponents and maximize their chances very well. Not only that but this tactic was also carried out optimally by all the players. So far, the players have been quite fair and solid in maximizing their roles and there is no strong desire to force themselves to stand out so that it will actually interfere with the game. Maybe there was, but it could be covered by the solidity of the other players and in the end, it didn't happen again.
Spalletti gives a very big impact to the performance from napoli but the problem will be coming very soon. So many clubs putting their eyes into the napoli as those clubs may be interested with some starting line up from napoli. That will force spalletti think to get the best rotation when some main players in the current squad will be gone. Spalletti is very happy with the current squad from napoli caused by it was still doing more and more winstreak against another team in serie a.
It seems like that the same trend will continue when napoli will be facing frankfurt which can be considered as a strong opponent. Frankfurt can't be underrated team.