Vlahovic wouldn't be a reasonable name for Barcelona in the first place. He isn't a reliable striker to replace Lewandowski honestly. There are much better alternatives in the market. 

About Nkunku and Gimenez, it is really sad to see none of them making a good level of goal contribution... Nkunku is still in the starting lineup.

Gimenez has been injured but he still played many games. I'm afraid he didn't impress at all like he did at Feyenoord.