Need to fill 3rd D Spot

I have Willis and Mayo.  I'd like to fill the 3rd spot and hopefully set it and forget it for the season.
Tackle Solo=1, Assist=0.5, Sack=2, Int=2, Fumble Force=1, Fumble Recovery=1, Def TD=6, Safety=2, Pass Defended=1, Blocked Kick=3, Return Yards 30yds/1pt, Return TD=6

Mason Foster
Patrick Peterson
Navorro Bowman
Rolando McClain
Wesley Woodyard
Nick Barnett
Patrick Chung
Laron Landry
Jamar Chaney

I have Peterson, who's gotten decent numbers, thanks to returns.  I'm worried about consistency every week.  I know that some of these guys are in there thanks to other injuries.
Thanks!

Pick up Barnett. He is going to have a monster week against New England.