Last season's Premier League runners-up needed a debut goal from substitute Darwin Nunez and Mohamed Salah's 80th-minute strike to twice come from behind and cancel out Aleksandar Mitrovic's brace at Craven Cottage.
When asked how frustrated he is by the disparity in performance, Klopp said: "You want to know on a scale of 1 to 10? 12. Very, very because the performance was a defeat. That's why we have to figure it out.
"The results are very important for us, obviously. I'd love to get three points, but I would have loved much more to play really good to be honest. We didn't do that.
"It is my responsibility to find out why we played last Saturday a surprisingly good game for the moment we were in in preseason and seven days later we look like we are completely upside down. That doesn't make sense. I speak to you now but I'm actually only thinking about that."