Anyone who had as good an amateur career as him can never be considered one dimensional. He has a good jab and decent movement when he has to use it. And Carl has a kind of an akward style that make s up for his lack of hand speed.
The weird thing about Froch's handspeed is he used to be faster. I watched a fight from early in his career and he was noticeably quicker. He was also more wiry though and probably not as sturdy.
This is where the Cobra nickname came from, ain't it? I used to think that his right hand was blindingly fast when he threw it out of that sort of half-coil he does. But now, to me, he looks a bit lazy with it.
I think that can happen to some fighters as they get older and start to fight at a higher level. Early on in their careers they can sometimes sacrifice their technque and power for speed. They have to adjust to the pro game and adjust their style from the am's. Take kelly Pavlik for example, early on in his career he was one quick combination puncher in when he was a novice. And as he went on he became a more slower fighter who sat down on his punches. Calzaghe could be at the other end of the spectrum then I suppose. He was a far harder and more correct puncher in his youth, but was forced to adjust later on to accomodate hand problems. Carl is also not a young fighter anymore, so his speed could very well have decreased because of it.