Packers offensive coordinator Tom Clements answered a question about WR Randall Cobb lining up in the backfield:
CLEMENTS: "Well, it gives the defense a different look, and he not only can release in a pass pattern out of the backfield but we use him as a runner sometimes. The defense, they have to respect the run because he's gotten some big runs from out of the backfield. As a pass receiver coming out of the backfield, they just have to account for him and it's a little bit different alignment for them at times. He's a dangerous weapon and we try to use him as best we can."
It's just another way good teams find a way to use good players. Cobb has had a very nice season and has rewarded fantasy owners who waited a bit at the position. Cobb and the Packers have some pretty favorable matchups the rest of the season so owners shouldn't have to even consider playing other matchups in their playoffs.