I like Gyökeres, but I'm still not sure he's a player who can compete in the Premier League, especially Arsenal. While Portuguese league defenses tend to be quite spaced out, the PL isn't.
You have a point, but besides what @mandown mentioned about the Man City game, he did spend a few seasons in the Championship with Coventry before moving to Sporting, so he's probably not going to have a hard time adapting to the pace & physicality of the EPL.
BTW, there are some unconfirmed reports about Dortmund and a few EPL clubs monitoring Trossard's situation at Arsenal, so he might end up leaving us this season
[not sure how I feel about it since I prefer we sell Martinelli instead and use the generated cash for Eze and another LW if we get lucky].