I'm not as well versed in the full mechanics ...
But I know what I look for in prospects ...
Man, when I look at a prospect, is about feet, hips, hands and eyes. Press is a technique that guys can learn after coming in, so "can a guy press... physically" is about arm length and functional strength first for me with prospects.
Feet and hips ... can you stay in phase and recover when he makes his break? Hands and eyes ... Are they grabby? Can they locate the football and finish the play?
Zone for me is mostly instinct and information processing along with understanding the defense and being assignment sound. But, of course, hip and ankle flexion, and ball skills come in here as well. Also I judge tackling as more of a priority in zone because if you run zone they're wanting to get a matchup on the outside with a RB against a DB.
I think when it comes down to it, you can hide some things in zone that get exposed in man (stiffness out of a break puts you 4 yards from your receiver rather than 1 or 2). But you can have an instinctual set of zone CBs that can tackle and play really stingy defense.
I expect better answers than mine but I figured I'd share my scouting. I actually watch the DB drills closely for hips and feet at the combine.
Note that there are 2 slot Safeties (Sainrstil and Hardy) that I believe have CB feet and hips and can play man ... but they weren't asked to because PSU and Michigan go length and power outside (usually).