"It was very frustrating," he said. "It was a game where we were much the better side but lost our concentration at the beginning of the second half. I thought we'd moved on from that, to be honest.
"We had total control in the first half and were deservedly in the lead, but we were so loose at the beginning of the second half it was frightening.
"Our concentration was very poor and before we knew it we were 3-1 down. The last 20 minutes was very good but it's too late by then.
"I thought we were lazy. Lazy in our play, loose and sloppy.
"We didn't do what I call the dirty bit: we didn't track runners. If you don't do that, if you don't earn the right...
"Whether we thought the game was too comfortable? At this level it never is."
Asked how he could address the defensive problems, Rodgers added: "It's constant reminders and constant work. Some of our play, our movement and passing - you can sense the excitement within the players and the stadium.
"But you can't keep having to score two, three and five goals to win games.
"Defensively, as a group, we need to be better.
"I will be open with my communication with the players, but they are disappointed as well."