You don't have to produce consistent brilliance for people to be able to spot potential though do you? That's what potential is effectively, if you're already great then potential doesn't really come into it. If I think of someone like Stones here, it was always clear that he had huge potential and could be a massive star, despite the fact he rarely gave dominant performances and made semi regular massive errors. For me, Onana's potential is massive. Whether he fulfils it is a different question, and he certainly isn't at megastar level at the moment, but I think it's easy to see why people are excited about him personally.