It was once used as a tool by agents, but now it's reserved for players who are usually academically ineligible or have been kicked off their college team for some reason. These are now players who may have some character concerns that might keep them off a draft board, but the Packers have shown interest in at least one of the six eligible players (South Alabama DB Damond Smith). Via Shutdown Corner:
On the defensive side, Smith might be an intriguing prospect. The 5-foot-11, 181-pound cornerback began his career at Western Michigan before transferring to South Alabama, where he got into a fight with a teammate and was suspended for violating team rules. Smith was invited to tryout for the Green Bay Packers following the 2013 entry draft, but the ruled that he was eligible for the supplemental draft.He might not sound like a winner, but the Packers haven't shied away from players with troubled pasts (see DE Johnny Jolly as one example). There's usually two sides to the story. I'm sure the Packers have done their research on him, if his talent is enough to justify a roster spot.
He doesn't strike me as a player that would require a high draft choice, though the Packers might just wait and see if he goes undrafted. There's no pressing need for another DB, but it's a long preseason and there's always a need for more bodies (as the roster limits allow). Plus, there's usually room for an undrafted free agent in the secondary (M.D. Jennings in 2011, Sean Richardson in 2012). Smith is someone to watch for later this week.