Jorge Mendes isn't Otamendi's agent but he's close to both clubs involved and has therefore been dragged into everything, but Valencia's sporting director Amadeo Salvo has been quoted by
Super Deporte as saying "Mendes is nobody in Valencia."
Salvo also said that if he sold Otamendi for less than his clause, even €49m, then he'd be sacked by the Spanish club's owner Peter Lim. He also expects that Manchester United pay the transfer fee all in one go "if it's Manchester I think it'll be 50 in cash."
There is a little light there, he's making it sound like Valencia would treat a €50m bid as a conventional transfer rather than force the buyout clause route.