The German manager rotated his squad in the wake of Thursday's Europa League semi-final win over Villarreal and was left encouraged by the performances of his youngsters in the convincing win over the Hornets at Anfield.
He said: "We had to give them the opportunity and they took it. They took the chance.
"Ojo, everybody saw already what a wonderful player he is. Connor Randall only a few minutes.
"Cameron Brannagan, I told him when he came in 'It's not your position, sorry'. But after the game I had to say 'Forget it, you can play this position too'. It was really good.
"Kevin Stewart worked so hard in a central position. We did everything, everything was better."