You can tell when guys look at a list of names with stars, who have obviously not taken the time to watch a highlight tape or two.
Mosleys going to be an engineer, obviously he's smart. So you can conclude that they worked him out saw him run a legit low 4.3 40 then went over film and asked him about defensive schemes. Being the smart kid he is you can assume he knew his concepts when TJ sat him down in the film room. With that info at hand you can make a reasonable assumption the kid wowed Bo enough or showed the ability to pick up a concept quickly to get an offer on the spot, despite being a tad undersized. Bo's got two CB starting in the NFL in his short coaching career. I will trust his judgement.
No way in the world the kid walked in your average football player and said " ya man I just make sure the guy I'm covering doesn't catch the ball, then tackle him if he does" More likely he showed good zone scheme understanding for a HS kid , doubt TJ would put himself thru the agony offering a kid that had two star potential to try and coach up.