It's all about where the wingers are in relation to Vlahovic, they're making runs far ahead and running on to goal. Our wingers are not like that so Vlahovic has nobody to pass forward to. Since he's the main focal point, he usually has two defenders on him, if our wingers are more advanced, then the defenders will back off and give Vlahovic more space.
With overlapping and actual wide players, Vlahovic would be far better. It's basic football and Motta can't seem to figure it out, so I can't see any strikers coming in that will do better than Vlahovic.