The Magic are rebuilding and are going to be horrible. When judging a player's importance on a rebuilding team, things other than simply skill set and talent come into mind. Rather, the value of the player towards a rebuilding effort is what must be considered. That must be first and foremost when evaluating the talent and merit of a guy who is up in years and slightly better than average (see: Jameer Nelson, Al Harrington, and Hedo Turkoglu).
Thus, by taking into account the actual value of a player and his prospective role in the rebuilding effort, we can obtain a sense of who actually matters the most to the people in charge: head coach Jacque Vaughn and Magic GM Rob Hennigan. If neither of these guys are on board, the guy's career is over, or at least his days in a Magic uniform.
The Magic have no need other than to have one of two types of players: veterans with leadership and mentoring capabilities, and then, guys for them to mentor. It's a very Mister Miyagi meets Daniel Son way of building a team, but is also as old as the hills: have a young guy learn from someone who has already succeeded and is a high character person.
That, again, is the category in which Nelson, Harrington and even Glen Davis fall into. The Magic's young guys need mentors like them just as much as they need their proteges (see: Moe Harkless, Nikola Vucevic, Andrew Nicholson, Kyle O'Quinn). It's commensalism.
All in all, the list becomes a bit more defined as you consider what gives a player importance in an effort like this, as we see franchises have to do from time to time.
Only a rare few stand strong over decades (Think: San Antonio), and teams like Orlando have a blueprint for when they go from the ground up. It will take years, but in the meantime, this slide show gives you a rough estimate of the importance of each player to the organization first, and then to the actual team.