I assume Donny kept up with Spears contract and recognized he's a free agent. So he was just recently signed (the same day Nnamdi went to Philly) and since Nnamdi is still on the Raiders I wasn't surprised Spears wasn't on.
Look at the Browns if you want to see Elam, he's an 80 OVR Free Safety
Not sure at all why Brent wasn't included. . . strange. . . nonetheless he will be on the day 1 roster update (online).