Gyökeres had a truly disappointing start to the season with Arsenal. He wasn't effective at all against Manchester United and didn't play well for Arsenal at all. That's why the manager substituted him in the 59th minute. I can't criticize him for that, as he doesn't look ready yet. It seems like it'll take some time for him to get ready for the tough competition of the Premier League.
Gyokeres is a player that many expectations are expected from him and that makes it very observant to everyone when he performs less in any game. This may be his first season and first game in the Premier League which was suppose to be overlooked for him, but he’s blamed by many already that he’s a poor player that can not do well in the premier league. Gyokeres should be giving more time in my own opinion, because I feel he’ll do better with time and have to first understand the pattern of the game before we can rate him again. He will not have a poor stay in this club but he will continue to develop overtime.
Every one deserves a second chance and even a third and forth chance if needed, the player in question is absolutely new in premier league and like you said, he may still be struggling to understand the pattern at which the game is being played, premier league is a tough place to play in as a football player, but those who dear have the ball to continue and determine to do well always will achieve world bet.
I haven't seen any Gyokeres games and don't know how talented he is, but for him to be signed by Arsenal and having alot of football fans looking up to him, I believe he is a wonderful player and only need some time learn the basics of playing in the premier league and also adopt the style.
It is commonly Said the environment we live in influences us alot, and based on this fact, Gyokeres may still be stuck and player based on the environment he came from which unfortunately is not relevant in the Premier league, he will need more time to adjust accordingly.