The 60-year-old Italian told Sky Sport Italia: 'We changed the players, but not the basic structure of the team.
The night began badly with Liverpool's Brazilian holding midfielder Fabinho limping off in the 19th minute with what appeared to be an ankle injury.
The Reds were far from their fluid best and that's credit to Ancelotti's Napoli side, who put in a stubborn defensive performance following a hugely hard few weeks off the field.
The holders and Premier League leaders have a hectic spell of fixtures on the horizon including the Club World Cup, a League Cup quarter final and now, a crucial Champions League fixture.
"They closed the center so we needed to come from the wing", Klopp said, via the BBC.
Wijnaldum acknowledged it was a "frustrating" position, given Liverpool knew a win over Napoli would have made sure of their qualification and taken any edge off the Salzburg game.
Liverpool went behind on 21 minutes thanks to Mertens' smart finish but couldn't find a victor after Lovren's header had equalised 25 minutes from time.
"Of course they get the credit but we didn't do the things we did in the beginning so we will see".
"The problem was we had the wings open, we tried to use them with the crosses, but we crossed the ball too early most of the time".
10 minutes after the restart, Liverpool wasted a glorious chance to score the leveler, when Roberto Firmino found a loose ball inside the box after Meret failed to catch Jordan Henderson's cross tightly. I can't remember one game since I was here when we could go in with 50 per cent. Like I say, we're still in a healthy position but we need to get a result away now.