Well it’s simple, Isak has done it at a higher standard than the Bundesliga, at a time where the La liga was still strong, with Messi and Benzema and he’s done it consistently in the premier league.
Wirtz has played well in a league where Jadon Sancho looked like Maradona, and has yet to prove his worth in his outings in English football. As of yet, the pace has looked too much for him, whereas Isak has been thriving for years.
Wirtz will inevitably come good but he’s without a doubt less proven.
The premier league has broken bigger stars than Wirtz, don’t forget.