What is a franchise player? While the definition may vary from person to person, at its simplest, I believe it is someone whom you build a team around.
To build a team around someone, he needs to be under 30 at a minimum. Preferably, he will be under the age of 25.
There should be glimpses of greatness and an overall perception that this person will become the cornerstone of your team. Having a great personality does not hurt either.
Some will disagree with the notion that each team already has a franchise player. That is fair, but take a look at each team's franchise player and let's start the debate!