In reference to sports:
Someone who only watches a few games here and there, but still views theirself as an expert and constantly voices their illinformed opinion on sports topics
LeCasual: All Giannis does is dunk, he has no bag
DurExpert: Shut up and actually watch some ball, casual.
Somebody who knows absolutely nothing about mixed martial arts and only knows the basic fighters like Conor McGregor, Khabib, Sean O'Malley, Israel Adesanya, Islam Makhachev, Khamzat and worships them as gods like used in the sentence example.