They went a goal down away from home to a Lazio team who missed out on top 4 on the last day, brought it back and won, and you see that as a bad thing?
The Milan game .. again yeah they shouldn't be going down 2-0, but showed tremendous fighting spirit to win 3-2 in the end. Two wins against two decent Serie A teams. Ancelotti has a good record in the CL and they're still the same team on paper. Liverpool are definitely better I'd say, but would it shock me if Napoli won at least one of their games? No.
Any team with Cavani/Mbappe/Neymar is going to cause a side problems, and the likes of Verrati, Rabiot, Thiago Silva, Marquinhos etc are hardly poor players either. They also now have Buffon to give them that little bit extra experience in the side. They've regularly lost in the knockouts but have a solid home record in the groups I believe, so again at home they can definitely beat Liverpool.