Typical sensationalist headline, read what Silvestre actually said. It's about context dude. All he's saying is that Arsenal needed another striker and that was more important than buying an attacking winger/forward e.g Sanchez because Arsenal already have loads of those. So the headline tries to make it seem like Silvestre thinks Sanchez is a bad player and signing him is a mistake whereas in reality he's saying Arsenal made a mistake signing an attacking midfielder before they got in another striker. I agree with Silvestre, it is more important for Arsenal to buy a top quality striker because Giroud will not win them the title
how the heck is sanchez a mistake, one of the best players in the WC