Ray was at his absolute best at welter and light middle. At 168, Froch beats him but Ray had a good chin and avoids enough of Carl's big shots to go the distance.
LaLonde couldn't carry Froch's jock. And the Lalonde that fought Ray was purposely drained, agreeing to absurd terms in order to get a career high pay day. Froch would likely do a Bute on Leonard... big ring or small.
A lot of folk picking Froch here. I'm going with the best version of Leonard possible coming in under 168lbs to beat Froch. Smarter and faster with more skill. However maybe the natural bigger man in Froch comes through. My pick is Ray.