Originally Posted by Rama04

It's essentially a projection of the next few upgrades. In the event somebody quits, drops from the award, doesn't have the time to upgrade ETC, their spot will be taken by an alternate. The alternates are listed at the bottom of the award.
It's a pretty safe bet on where you'll see the junior awarded captains start for the next vacancy. Interestingly enough, the 5 or so alternates traversed a months worth of new hires.... Hence why some people expect street captains.