I can see that argument, I'm just not sure where it comes from.
If Surtain is better right now and has shown he's plenty athletic, why is his ceiling lower? Cause he runs a tenth of a second slower in the 40? If he's already better technically, and at least equal as far as instincts, why is his ceiling lower? If he already poses elite traits that some NFL starting corners don't have, why wouldn't that immediately lift his ceiling.
I feel like because Surtain already has such good technique, people have written of his ability to get even better. But, because Horn is starting with a lesser toolset, it's easier to envision him getting better.
It happens every year with prospects and it's the most unusual phenomenon. Player A is a technician and therefor pretty much at his ceiling. Player B is as technically sound but runs a little faster. So, player B has a higher ceiling. WUT?! The fact that he's such a technician should further increase his potential. You KNOW he's gonna study. You KNOW he's gonna learn. You KNOW he's gonna get better.