Edwards lost by 24 points, Mayo lost by 28 points. This despite the fact that Edwards was running in an R+19 district and Mayo's district was R+14. Racist Louisiana strikes again.
Edwards' length of "service" to Louisiana might also have played a role. I think I commented elsewhere that if he'd switched parties upon leaving prison, he'd be headed to the House right now. Whatever other Democrat would've ran would've gotten first/second place, and he'd be the top Republican.
If he'd switched and waited till 2015, he could've had a reasonable chance of returning to the Governor's Mansion (probably the office he really wants).