They'll be paying huge wages for a washed up Auba for however long his contract is. That's not wise.
I'm not sure on De Jong the player. I was projecting a little when I spoke of City and Liverpool not fancying him. He's obviously an excellent player, but I never quite got why everyone went so gaga for him? He relies of his decent burst and dribbling rather than insane touch, close control and balance like a Bernado Silva does, and I'm not sure how well that'd translate to the PL where everyone in midfield is a top athlete? I also think he's prone to giving the ball away in dangerous areas - it rules him out as a potential top 6 for me - and I've never seen a true elite passing range or final ball in him.
Maybe I've got him wrong, but I've just never quite seen it with him as one of the very, very best.