Nunez potential is not hiding at all,he has been phenomenal ever since his days at Benfica,he scored goals on regular basis.I love the way he plays and connects with other players in the team.we all wait to see what he will be able to do in the premier league.He is a very good player,we know but premier league will test his abilities.
Of course pre-season games are different from official games. And maybe things are a little more difficult at first for Nunez. But I believe that the coach will work well with the player, for in some days he will be an incredible player.
To a large extent, the pre season doesn't determine that outcome of the league. Some teams perform poorly during their pre-season games and turn around to do much better later in the league. This is the case of Liverpool, they might not perform well in the pre season game like in the game against Manchester united but when the league starts it will be a different case, their performance level with be different and top class.