Of that group, only Rau ever actually played in a regular season game or was even on the active roster. Rau made sparse appearances in the last 4 games of the season. As Jeff McLane notes, Rau's most memorable contribution was when he forgot he was supposed to be out on a special teams and as a result an Eagles punt was blocked.
So when Chip Kelly looks over your film and that's all there is... It's not particularly likely you'll find a place on the team.
These really aren't even roster players so they're never more than day to day with the team as is. Expect them to be replaced by similar street free agents or UDFAs.