It's a bimodal curve where he has high highs but low lows, which averages out to being...average. Usually if a player is good, bad, or average at certain aspects of the game, they'll be good, bad, or average at most aspects of the game. But it's baffling for a player to be simultaneously so great in some aspects and so disappointing in others that people (often very vocal people) don't know how to process it.
What I think you're ignoring, and what actually pisses me off in this thread, is the people that demonstrate genuine antipathy towards Ewers. Saying stupid shit like he "cost us a national championship" or delighting in his draft plummet are bizarre behaviors and belong more on TexAgs than on here. Especially when guys like Sark, Jahdae Barron, and the rest of the QB room all consistently sing Ewers' praises and talk about how much he's done for the program. So even though I think you're correct about Quinn's performance as a QB, I think the "emotional garbage" that's being drawn out in this thread has more to do with people shitting on Ewers (because they have the emotional intelligence of a particularly callous hamster) and people defending Ewers because they don't like seeing their QB get shit on. And I find it pretty easy to side with the latter group.
Also, here's another Quinn gif. Been sitting on it for a while: