@IanCundall
Brayan Bello and Jeter Downs are locks to be added. Josh Winckowski and Kutter Crawford are near-locks to be added, and I would be very surprised if they weren't. All four of those players have a realistic chance of helping the MLB team next year.
After those four, I think there are nine players who you could make a case for in either direction: Thaddeus Ward, Gilberto Jimenez, Ceddanne Rafaela, Victor Santos, Durbin Feltman, Zack Kelly, Frank German, Ryan Fitzgerald and Kole Cottam.
Right now I think at least two, and potentially up to four, of those players could be protected. Also, if the Red Sox look to make a trade before the deadline, I'd expect it to be from this group, since whoever doesn't get protected would have a decent chance to get selected.
I would go:
Bello
Downs
Winckowski
Crawford
Cottam
Feltman
Santos
There are currently 7 spots open. They could add those guys without dropping anyone. I think Hudson Potts, Jeisson Rosario, Phillips Valdez and Austin Davis are DFA candidates.