Are you honestly comparing Amirov with Kaprizov? Both Russian and played on the same KHL team as 18/19 year-olds but that's where any comparison ends really. The circumstances of them both "taking time to come over" are completely different, Karpizov wanted to finish his KHL contract and step into the NHL as a star.
Amirov is still struggling to find ice time in the KHL as a 20 year old, Kaprizov was a KHL star as a 19 year old and was a full time KHLer as a 17 year old.
Ufa careers at the same age:
18YO
Kaprizov 53GP, 11G, 16A, 27pts
Amirov 21GP, 0G, 2A, 2pts
19YO
Kaprizov 49GP, 20G, 22A, 42pts
Amirov 39GP, 9G, 4A, 13pts