besides the problem in the defense line, I think the transition when attacking to defending that Napoli implemented was not successful. there was a delay in filling the gaps left when they tried to attack. while they also had problems in finishing.
Conte has a lot of work to do in the Napoli team. it will take time and will not happen in a short time. replacing some players may be a short-term solution, but the coordination of the game between players must be trained much longer.
Obviously conte is yet to get it right with Napoli of which is normal, even Chelsea who has their coach changed are also suffering similar thing, I will want to believe it's just the beginning of the season and so they should be given some more time, just maybe they will do better than they have been doing, Napoli's defense line has got some adjustments to make and the fact they they are not having a firm attack to will burden the defense or maybe is a tactical problem, whichever it is I hope conte gets it fixed soonest least they end up the same way they did last season.
Any new coach when coaching their club needs time to adapt well and the club should not be too hasty in pressuring the coach because it can affect the coach's strategy that will fix the club, even though Antonio Conte is an experienced coach in Serie A and has achieved many achievements here but still every club he coaches has differences and is not the same.
Antonio Conte must start everything from the beginning in Napoli and the club must also fulfill the requests and what the coach wants so that the coach can work optimally according to the characteristics of the players he what he wants.