Claudius he does score a lot of goals in open play / counter situations, and also being open in the box. Additionally, he is just much bigger, stronger, faster than his typical Portuguese opponent. I heard recently that Porto/Sporting pay £35m in wages while their typical opponent pays £5m. To put into perspective, the top teams in Championship pay £35m and the bottom teams pay £10m. If we assume some efficiency in the market, then Gyokeres is effectively playing against Championship level opponents for the most part.
But even then, his strength, speed, finishing are all worth a look. He is probably worth 15+ goals, but I don’t expect him to drop 30 in the league.