A 'lock down' corner, by definition, is a corner who plays man coverage on the opponents no. 1 receiver in an attempt to deny him the ball. I don't know where you got your definition? I know your a coach and I normally enjoy your posts, but you are incorrect in this one. I have gone to Iowa's camp/clinic numerous times (and many others) including this year and they haven't changed their schemes from when Norm was there, except for the raider package. It's the same scheme that Speivey, and Prater and Hyde, etc. excelled in. There are no special schemes for King, although like Prater, King is good at 'disguising' coverage. As I have mentioned a couple times before, he (like Prater was) is good at baiting the QB into throwing to the corner route when they run smash routes against cover2. He acts like he is 'sitting down' in the flat but quickly breaks under the corner route. That has accounted for 3 of his picks this year.
They play cover2, quarterscoverage, 1/4,1/4,1/2 (normally against trips), they'll 'roll' to cover3 when they blitz, and they have been playing a lot of cover2, man under (especially in the raider package), just like they always have. You are correct that he plays a slot receiver when they play man under in the raider package, but that's the only time he 'moves around'. I know he had one pick from the raider when he jumped under the quick out to the slot receiver.
As far as your blitz comment, I have no idea what you are talking about. When who blitzes? The LEO? The Mike? the corner? Almost all the time when they blitz (except in raider) they roll to cover 3 with the SS rolling to the zone vacated by the blitzer. What it sounds like you're describing with the 1 high safety shading away from King, is their 1/4,1/4,1/2 coverage because the safety has the 'inside' 1/4 and yes King is left on an island in that coverage as he has deep 1/2 on his side of the field. It's pretty much man on his side of the field since they only run this when they only one receiver to his side. It probably does look tempting to the QB with the corner playing fairly tight with no safety help but King (like many before him) plays it extremely well. He can play loose because he knows he is getting help underneath from the will or the ss depending on the call. It was this coverage they were in when Sash picked mich. st. and flipped the ball to Hyde and King had one pick in this coverage that I remember when they tried to go vertical on him. As far as King being his presnap read, totally depends on what play they have called, don't you think. If they are 'tagging' a receiver to run a vertical or hitch, yes, that would be an occasion when that is probably his read, etc...