I couldn't care less about CORSI personally.
The issue with Aho is that he doesn't do anything wrong for the majority of the game but then there's always a play that a normal defenseman could handle that he simply can't and it leads to goals at crucial moments. It's not that he has a brain fart (though he has those too), it's his inability to actually perform the function.
The biggest example is he can't contain any big forward at all and has to hold on for dear life when things start to get physical. That's not because he's in the wrong position or made a mental mistake, he's just physically overmatched and it happens constantly. That means he can't play in crucial situations because he'll just get abused.
Despite his great CORSI and better than most giveaway/takeaway ratio he's second to last on the team in +/- at -13. The next closest defenseman is Reilly at -10, but at least Reilly can put up some points while being a defensive liability. He's also not going to get toss around the ice like a ragdoll the same way Aho is.
You are right on your assessment, however, he was never given the opportunity to make his skills shine. Look at his career. He has always been an offensive defenceman, but this team, most of the time, puts him in weird defensive situations ALL the time.
You can tell he's been working on staying up with the club, playing in a style he's not built to do and I admire that because he wants to be here. His shot is super accurate...but our guys never crash the net and or they miss the net on the deflection. He never shoots at the net to score..he's always looking for a stick and if you watch...they hit the majority of the time.
I completely agree with some defensive gaffs, especially when Owen Tippet is on the ice.. That kid is FAST..none of our guys can handle Tippet if it were not for their reach. He just doesn't naturally think defensively.....You HAVE to be aware at who's on the ice and if there is a fast player, you need to know when to start hustling back BEFORE it's too late.
As for the +-, I'm not sure because a lot of those goals against weren't his fault at all. It feels like a mixture of forwards not back checking, lackadaisical play of other players, being too cute etc etc. AT the same time...I'm starting to think that maybe for this part, it might be the coaching...anyway...lets see...I really want to see what we are after 10-15 games.
I do see him struggling to make offensive plays..but I don't think that is lack of offensive skill. Come on..we know he has it..hes impressed us every so often, but I see he is really edgy/confused...maybe not used to playing a 2 way game..it's either defensive or offensive (one or the other..never both). He seems to be struggling on timing of when to jump into the play and when not to...YOu can see at some points, he hesitates...I think this has something to do with Trotz drilling in defense into his head and it's conflicting with his offensive skills. Also, when he first came up..he was only supposed to play a defensive game.
Anyway...I am seeing that Roy is having him try things. You see that he sometimes jumps into plays (playing like a forward)...and yes, I'd be open at trying him on wing.