Sporting played Gyokeres usually with balls launched behind of him where he could physically (speed and strenght) overpower the defense. I don't know Arsenal that well but that doesn't seems to be their style.
In fact when Amorim left the (very short lived) next manager tried to use him in a more conventional style and his numbers suffered. It wasn't only that, the team had been set for 343 and nothing really worked but you could see how uncomfortable he was.
Btw Sporting beat PSG yesterday. Great showing.
To see how uneven things are Sporting used a player whose cost was 300k euros or in EPL money, 0.26 million pounds.
Well, yes.
However, current Manchester City and Erling Haaland notwithstanding, (besides, in his earlier incarnations as City's manager, Pep Guardiola didn't promote the use of such a striker favouring system), top teams don't usually choose to construct their team around a striker.
Rather, in the best teams, a star striker is simply a part of the team, a player in the team, not the fulcrum around whom the team revolves and exists to serve.
Anyway, Gyokeres is a long way from that.
In any case, I am also rather struck by the fact that, of the goals he has in fact scored so far while taking the field in an Arsenal shirt, Gyokeres has never actually scored Arsenal's first goal, (last night's goal was Arsenal's third). In other words, he seems more comfortable - or confident? - scoring, when Arsenal have already secured an advantage in the game, and lead relatively comfortably. Critical, goals, goals scored under stress and when under pressure, with the game balanced on a knife-edge, are goals I have yet to see him score.
Moreover, with the possible exception of last night's game, he hasn't really scored a goal in a game that I would consider, or deem, critical, or vital.