Even with those problems, they managed to draw with Barcelona. I don't think Barcelona have any serious problems that prevent them from winning, at least they are playing better than Napoli. Napoli are awful this season, as their play shows, I'll be surprised if they go any further
I won't underestimate Napoli because they managed to draw the match at home. Their performance may not be as good in league games, but they are performing very well in the Champions League, and if they wish, they can eliminate Barcelona at this point because what Barcelona played against them will not be sufficient to hold them back and prevent them from progressing to the next round of the competition when they repeat the same in the day of the second leg. If I were to rate each of their performances this season, I would give them the same score, even though Barcelona is in a better position in the standings than Napoli. My score could be attributed to the competitive nature of each league which I feel that of Serie A is more harder to play in than that of La Liga.