The NFL is different from other professional sport leagues like the NBA or MLB in that there is no farm system for players to develop before entering the highest level of competition.
In baseball, the minors comprise three separate leagues (Single-A, Double-A and Triple-A) in which players can compete against lesser competition before being called up to the majors. The D-League of the NBA is similar in that franchises can choose when to call up prospects.
This lack of a farm system makes it more difficult to differentiate which NFL players are truly developmental "prospects" and which have shed this label and are well into their development as professional football players.
Therefore, I'll set out a set of standards that players must meet to be considered prospects: Players must be less than 25 years old, have started 10 or fewer games in the NFL and must not have been picked within the first three rounds of the NFL draft.
The players on this list are ranked based on their ceilings as professional football players, their ability to remain in good health and their potential to contribute to the Carolina Panthers organization.