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!
Overall this season there are not many changes to the Napoli squad they just released 3 players and brought in 3 players as well and Napoli can try it in pre-season matches, I don't see any mental constraints on them except on strategy because Napoli has a new coach so at least he has to understand the character of his players first it may take more time. If we monitor player transfer activity in Serie A, it seems that there are no competitors who are strengthening their squad instead most of them let go of important players as we know, financial problems are the main factor.
I think it's very important for Napoli that the new coach can get the whole team right as soon as possible. If it doesn't happen quickly, there will be almost no chance to win. Also a good example is the last legendary coach of Manchester United, after whose leaving they never won the Premier League. It seems to me that Napoli could be something like that.