For any championship club there going to be new problems every other season. The only way that the club is going to be one of the best is by fixing those problems.
Of course, Napoli must prepare well for this season, however, being a defending champions, this will become a burden for players who have just joined. Coaches must be able to increase the confidence of new players so they can play well as a team. BTW, Napoli had a friendly match against SPAL with a final score of 1 - 1, maybe this cannot reflect Napoli's strength this season, but this match should be enough to serve as a "warning" for Spalleti. The real challenge will come!