I don't see the matchup being worse than 6-4 in favor of Quan. Quan is extremely powerful, but he doesn't have armor , a wakeup option, or good defense. All of which you need when cornered. But mid-full screen Quan has a clear advantage. I think the stage could have a lot to do with this matchup.
The three weaknesses you gave are all the same thing... How does one not connect "armor" to 'defense?" And let's be real, you use armor on "wake up." There's an adage that states the best defense is a good offense and no one would disagree with the fact that Quan's offense is -ahem- "good." And the last time I checked, his block button is the same as everyone else's. Let's not forget about his ridiculously fast and safe 6f poke either. In multiple variations, Quan sees top 8 regularly, and it's because his worst match ups are still in his favor. No other character in the game does this with such alarming regularity.
In Summoner, he boasts repeated same frame OH/ low mix ups, doing roughly 5 repetitions to kill, and the only way out of this is to send him full screen with a breaker where he excels as one of the best zoning characters in the game. Zoning illustrated most clearly by his ~50%
unbreakable combo that starts
from zoning. Not only that, but if he decides to do so, he can use his zoning to perform the pseudo unblockable for just 1 bar with the crazy block advantage ex rune has. This requires minimal setup in summoning a bat, and can be accomplished on either block or hit.
In Sorcerer, he has the ability to set up the scariest corner game MKX has seen yet using his armor spell where he can safely mix up time and time again without meter. If for some reason Quan decides not to set up this armor spell in the corner, he can simply do it mid screen (off either a BnB or a MB rune hit) and zone like a monster
yet again. Hell, if he wants to, off of any successful mix up Quan can deal an "inescapable" 60% using his hex, dealing massive chip damage and putting himself safely mid screen again. If anyone wondered about the reason block breakers were in the game, Quan is a front runner. How do you stop him? Spend 2 bars and more stamina than you can afford on hit (OR block now) to send the best zoning character out there full screen.
"Extremely powerful" is putting it lightly. Kitana's showed a 90% combo on him, manipulating his own armor spell against him in a dream scenario. And the community unanimously regarded that as "fair." For the entire community to agree that a near kill combo, on anything for that matter, is fair should speak
volumes about how unbalanced Quan is right now. The only way Quan gets beat is if an opponent severely outplays the Quan Chi, and makes 0 mistakes. I'm not campaigning for nerfs. The community may discover new tech that blows these match ups wide open. Even now, Cryomancer SZ can deal huge amounts of damage to Sorcerer Quan. But c'mon, call it what it is. This characters risk/ reward is out of control and he's going to be adjusted. For the record, I like his design, but the loopable "unblockable" and insane damage need to be looked at.