Oh, you don't need to tell me about how good or bad he is. Mediocre might be a bit harsh but contrarily to his fans he's not on the level to be in the WDC fight on merit.
That said I do consider what happened to him more a case of bad luck than him doing anything particularly egregious. Should've he avoided the white line? Maybe. But you don't know how slippery the white line is until someone slips on it. Even godlike drivers like Verstappen can get caught by the white line and slip. It was just unlucky for Russell to be the first one to that line, that line being slippery and him ending in the wall instead of just spinning out. Had it been any other driver I would say the same thing. I consider it just a case of bad luck, not an indication of poor skill.