Spanish journalist Gregorio Salinas said in his column for the national newspaper La Gaceta that Juanpa was "not fit enough to lead the Spanish side" and "Spain need that leader who can put people in their place and help them win for the team, and I'm afraid Juanpa isn't that leader."
London Town defender Juanpa, 28, took the armband from Juan Antonio "Toni" Gómez in May 2009, after allegations of the Madrid Cosmos custodian's private life forced him to resign.
But Juanpa himself has labelled his critics as "idiotic" - particularly Salinas - after questions about his leadership.
"These idiotic journalists can say whatever they want about me, but I'm not going to listen to one of them," said Juanpa.
"The manager said to me that I was the best man to lead Spain, and I respect that."
