Klopp gave rare starts to Divock Origi, Xherdan Shaqiri, Adam Lallana and James Milner in the midweek clash, while Adrian replaced the suspended Alisson in goal.
Origi opened the scoring six minutes into the game with his first of two goals and it was Shaqiri who netted the Reds' second.
Sadio Mane and Georginio Wijnaldum were also on target as the Premier League leaders extended their unbeaten run to 32 games, setting a new club record.
And Klopp was delighted with Liverpool's performance against their Merseyside rivals, who have lost three games in a row.
“All the goals were incredible, outstanding. Wonderful goals, sensational passes, super pieces of football. I loved it a lot," he told reporters.
"We needed fresh legs and I had to show my respect to the boys in the squad, that's all. They proved it. It is much more fun making changes, all of the boys are ready to deliver performances like this."
He added: "Oh, a lot of great football moments in that game. We spoke before about the five changes. I had to show respect to the boys for what they do in training.
"I speak a lot about the quality of the squad so we have to show it. What they made of it was incredible. Divock's goals, Sadio's passes, Shaqiri's everything, Lallana was everywhere.
"So many good football moments but from time-to-time we were a bit rusty in defending. They were really direct and we had a lot of second ball situations."
Liverpool will play five games over the next two weeks as their Club World Cup campaign approaches and Klopp says he will have to keep rotating the squad as the fixture list gets busier.
"We knew these boys were good. We don't have a big squad because of injuries but young boys make impressions from behind too," he said.
"We know the quality we have. They really push from behind, so that's cool. That was the first game of a tough fixture list. We have to make changes and we will make changes.
"Naby Keita is the only one who is in outstanding shape and who didn't play. I made five changes and was not brave enough to make six changes that is the only problem.
"I'm really pleased for them. I was not in doubt about it. The boys need to, when they have the chance, show it. Not for me really but for the public. I am really happy."