He has nothing to say. Pep and Klopp try to influence the game, because there is something to improve and do better, something you trained on or discussed prior to the game in detail. They have a style and plan.
If your manager tells you to go out and enjoy yourself, what should he say during the game? Come on lads, run more? Shoot? Score goals? We are doing the basics on the ground. Except for some special tactic here or there in the big games, there is nothing to really tell the players that they dont know or that needs to be addressed in detail.