The Blucerchiati have for the fifth time in their history started a Serie A campaign with three consecutive defeats.
But Di Francesco says, “After leaking so many goals, we decided to change our approach to ensure more coverage and be less open to attack.
“We did well in the first half-hour, then had our chances to equalise after the opening goal. We were up against a very strong Napoli side, so it's only natural they'd create problems for us. Unfortunately, after the break we had good opportunities and the final ball was often not the right choice.
“When you come off so many negative results, that is going to affect your confidence. Emiliano Rigoni had a big chance to equalise and that could've changed the match, but we're just not lucky at the moment.
“I do think it was the best Sampdoria performance of the season so far. We are only at the start of the campaign, I know what this team can do and am sure we can do much better.
“I just hope we start picking up some points from the next game to help with their self-esteem."