I'd imagine it was the same way they came up with Everett. Probably both Snead and Wade's people like 43 said.
On Everett, the scouting department identified him as a high player of interest the year before. They brought him to McVay's attention and he matched exactly the profile that McVay was looking for in a TE.
So they drafted him. JJ doesn't get drafted if he doesn't match Wade's profile of what he needs in a safety. But Snead is finding players all year. It's his and his staff's job to bring players who they feel match the coaching staff's profile to the coaches' attention.