Didn't he win U21 Euros a couple of weeks ago?
Whilst I don't think Lopetegui is "pure shit", he is a bit average. Has done nothing to change the games throughout the competition.
As for the titles, Spanish youth teams are usually really good. Last U21 manager was Luis Milla, who won the Euro U21 competition in 2011. Then went into Olympic Games 2012 as a big favorite, but his team was ridiculously bad and they got embarrassed. Lopetegui is better than Milla, but just how good he is? When you are managing sides with Mata, Martinez, Thiago, Isco, De Gea etc., it's difficult to judge.
But what everybody clearly saw in this FIFA U20 world cup is that Spain were very fortunate to beat Mexico. They were poor vs Ghana and USA, too. He had about 4 warnings, but he didn't fix anything. Of course it is not his fault that Spain didn't score after so many chances vs Uruguay. Unlucky, yes, but his team was superior and a better manager could have got a better result.