I hadn't heard of Southward moving over to Cb at all...?

According to McClure. It actually makes a good amount of sense, simply due to Southward's physical traits.

The Falcons need help in the secondary alongside Desmond Trufant and Robert Alford, who is recovering from a broken wrist. The safety situation remains uncertain with William Moore coming off a separated shoulder, Dezmen Southward destined for a move to cornerback and former starting free safety Dwight Lowery looking like he won't be back. Kemal Ishmael and Charles Godfrey are the other primary safeties in the mix, and the Falcons are expected to target a taller safety in free agency.

http://espn.go.com/blog/atlanta-falcons/post/_/id/12197/thurmond-could-be-key-ex-seahawk-for-falcons

The thing is our front 7 has no rush and consistently leaves the secondary out to dry, no matter how good they are they can only do so much. Put our DBs on a team with even a semblance of a rush and they would be quite good.

Check out the videos in the comment I posted to another person;

https://www.reddit.com/r/nfl/comments/2y98pm/this_is_a_surprise_falcons_lb_sean_weatherspoon/cp7gyoq

Lack of pass rush had little to do with Alfords horrible play. It's odd, whatever pass rushing woes our team had didn't seem to effect Trufant - who had another excellent season, ranking in the top ten for CB's by PFF. Alford was 89th out of 119th when he went down with his injury, for reference.

The pieces are there, they just get no recognition because of the shit we have up front leaving then out to dry and cover for 45seconds a play. Fix the front 7, and the pieces in the backfield will fall into place.

I really think Alford is a decent Cb2, like I said though they need a rush to help them.

Again, you can't blame Alford's troubles on a lack of pass rush - it just simply isn't true. He hasn't shown the ability make up for his diminutive size and lack of physical-ness (tough and physical being two things Quinn loves in a CB), like Trufant or other other CB's can.