Have you heard about the legend Fabrizio Romano? This Man doesn't lie when it comes to football and players transfers. So far as Fabrizio Romano has reported that this club has signed certain player, just believe it to be true. The reason why Arsenal haven't announced it yet is because the player have to pass his medicals and sign all necessary documents before he can be confirmed by the club. Viktor Gyökeres transfer to Arsenal has passed the stage of "here we go" so technically he is already an Arsenal player and I believe the club will announce him in the next few days.