I think most Arsenal fans are just giving their opinion based on his stats when you check the goals Gyökeres have scored and how consistent he's been with it, that's enough for any fan to get exited and hype such player, the fact that he's even got experience in England before moving to Portuguese League is enough to trigger the hype. Anyways it would cause lots of pressure on the player especially if he fails to live up to the standards the fans want him to be he'll get lots of backlash from rivals fans if he doesn't score up to 20+ goals, that's not something new it's the norms in the Premier League, especially when a heavy amount is spent on a particular player.
That's why we can't really expect Gyokeres to score much caused by EPL obviously multiple times harder than his home league.
The most sensical comparison for Gyokerez's case is that Nunez. Nunez scored 26 from 28 matches in Benfica, it's almost 1 goal per game. However, he's a flop when he came to the PL. This is because the different in the level in the league.
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