We can partly test level of Islams wrestling from the match Umar vs Merab. Umar, Khabib, Islam came from one wrestling school, from Abdulmanap Nurmagomedov. In theiry their wrestling should be on same level. Merab is also great at wrestling (rewatch fight against Petr Yan) and has great cardio. Never seen Arman breathing heavily in late rounds. Islam never had top level wrestlers opponents, as well as Umar. If Umar passes Merab wrestling, then Islam should not worry about Armans wrestling