Summertop: If you look at a fellowship team on the main fellowship page, players who are not on for 30 days will have a gray background.

Unfortunately I believe that when the captain is picking their player, the gray background does NOT show up. One suggestion would be to make sure the gray background is there also since I know some people don't want to kick others off the team in case they come back, but of course can be confusing how it is now when they are picking players for a challenge because you don't know who is not active in the challenge team picking part of the process.