Huff and Spears were both signed as free agents during the spring.
Huff started the season as the Ravens' starting free safety, but was benched after just one week. Spears played in five games, mostly as a reserve.
The Ravens hope Brown and Trawick will help improve Baltimore's special teams, which have had problems.
Baltimore coach John Harbaugh said Wednesday, "What we'll always try to do is have the strongest roster we possibly can to be as good a team as we possibly can be on Sunday. We feel like these moves move us in that direction."