Moore recorded 24 tackles and three sacks last season in 12 games, including seven starts in his second year with the Buffalo Bills.
Moore spent his first two seasons in the league in 2009 and 2010 with the Tampa Bay Buccaneers, where he appeared in a combined 15 games as a fourth-round draft choice out of Southern California.
Fluellen has made six career starts and has 2.5 sacks.
Boggs has not appeared in a regular-season game.
The club previously signed free agent defensive end Turk McBride to a one-year deal earlier in the offseason.
Veteran Israel Idonije remains unsigned and shares the same agent as Moore.