I'm alway annoyed by authors writing stories about game like worlds because it's obvious they're not gamers. Leaving aside ridiculous notions like "some guy being widely recognized as the best player in a MMORPG", unique skills that only one person has, or mechanics that make no sense, the fact that they ignore how much research players put into games bothers me. With thousands of people competing for the top spot, and this being the primary entertainment of this world apparently, the influence of every member of the party should have been understood by everyone. There should be no secrets regarding what a party with their composition should be capable of, and if they are beating the average by a lot, it should be obvious to people, and themselves especially.
Also, still annoyed by the idiocy of the black mage and hero both hiding the fact that he was doing anything at all. Even if you are hiding your "true strength" because for some reason it would inevitably reveal you were trained by the previous demon lord (and that's bad... why?) you could have still told your party you were doing something. And even if your actual strength is revealed, can't you say you trained on your own? You absolutely must reveal who trained you if people see you're good at your job? The hero seems to have trained on his own, we don't know who trained him and no one seems to care to learn.
If you can't reveal your true strength, then either don't follow a carreer that puts you in the spotlight, or don't go all out while pretending you're not doing anything. He should have acted within the range of a normal black mage, and told his party what he was doing. Not literally pretend to do nothing while going all out.
