Have you watched him play for Partizan? Any interesting highlights.
I mean, regarding his time at Partizan, he was 16.
Starting for Partizan and, yes, he didn't score a ton of goals but he was a 16 year old kid who showed enough bright signs that Fiorentina bought him and he immediately broke out in their Primavera for 11 goals in 13 appearances. And he got called up and had a rough start to his Serie A time.
He was 18 years old, fresh from Serbia. Not all players are the exact same.
Some develop faster, some develop slower.
Haaland being a beast of a scorer at 17 in Austria has no relation to Vlahovic turning into a good scorer against Serie A teams last year. Sometimes it takes time. And yes its a risk. He could be a flash in the pan. But you take risks in this business.