We don't know how high up the pitch Moreno is told to play. You also need to consider that he more or less get no help at all from the one of the attacking three on the left. Henderson isn't match fit and cover the ground he usually do. Milner helps out on the right side and make a big difference there. If Milner helped out Moreno in the same way and another player helped out Clyne then the latter one would IMO look a lot worse.
It is a team game. The midfielders and attackers must help out covering the wings.
Yeah Arn, Moreno must have followed Klopp's instructions to the tee. Klopp told him to be constantly out of position, make horrendous indulgent tackles in our box. In fact he was rewarded for his performance by being hauled off the pitch before he did anymore damage.
I do agree that full backs need help from the midfield. Of course they do. Lucas spent a season or two drifting out to left back to plug space for us. Cylne doesn't leave his right side vulnerable to attack at every opportunity. If Moreno isn't getting help from his midfielders then he need to hold his position and pick the right time to go wandering up the pitch.