But aren't you mixing up two competitions here? Regarding La Liga, Barcelona was doing way better last season and their defense was particularly strong compared to the rest of the league. But in the Champions League they failed to advancd to the next round. Yes the group was easier this season, but they did make it and now we will see what their overall condition is. In La Liga it is not what anyone would have hoped for and I don't see a lot of potential for them to improve.
Napoli has its own set of struggles and this is what may ignite some hope within them. But Napoli is still Napoli and we will see one team that is in bad shape getting confirmed as one of the losers of this season.
we cannot mix La Liga competitions with UCL or other leagues because the conditions will be very different if they are already in UCL. a team that looks weak in the domestic league can become very strong in UCL and this situation cannot always be predicted but we can see it from performance in the group stage in that round we can see how strong the performance is to be able to continue in the next round and we also cannot ignore the surprise injury of players which can affect the team's performance.
what is certain is that Barcelona and Napoli are still in the same good condition, it's just that before the match starts we will definitely be surprised by something that will cause the team to lose.