Comparing the Pereyra signing to De Bruyne or Vidal is just stupid. Those are outliers. As is Tevez for 12 mil. As is Pogba for free. Etc. Etc.
If you talk about De Bruyne, of course no one knew just how good he would be for Wolfsburg, or Chelsea clearly wouldn't have let him go so easily. People thought he was just another young player who wasn't living up to his potential. He has now.
No one would have known Vidal would explode like he did here into one of the top B2B mids in the world, or Leverkusen never would have sold him for the price they did.
Tevez for 12 mil. We could have just as easily had a player who remained in his ManCity form. If he was playing like he has here, ManCity never would have let him go for such a price.
Pereyra is an excellent signing for 15-17 million. He's not some crazy bargain yet. But he's clearly easily worth that price and by no means did we pay too much for him. He's just turned 24, he's improving weekly, he's certainly got some skill, and some intelligence, and he's a very hard worker. He lacks end product at the moment. His price point is obviously that 15-20 mil range.