Arsenal spent only 65 million on Gyokeres. Would you call that a lot of money? Whereas we saw a striker like Antony who was bought by Manchester United a few seasons ago for 95 million. 65 million is not a lot of money for Gyokeres. He scored 39 goals and 7 assists last season. Liga Portugal is not necessarily as competitive as the Premier League. Maybe it was a little easier to score goals in Liga Portugal. But I don't see any reason to call scoring 39 goals in a season a bad performance.
Give Gyokeres enough time. If he can gradually adapt himself well to the Premier League, we will see better performances from him. I have seen Gyokeres' performances in several matches. He is capable of playing well. I think Arsenal will not face losses by spending 65 million on Gyokeres.