Originally Posted by BevelDevil
One aspect of both the 1hbh and 2hbh is proper weight transfer. Roddick does this poorly. Check out the 2nd top-rated comment on this vid, then watch and decide for yourself.
He'd be in big trouble if he used this kind of footwork on a 1hbh.
roddick is indeed showing poor weight transfer, but i also think he's using it to counter balance his rotation on the backhand, as you noted with his left arm muscling the ball. i don't see the use of it in a two hander though, at least the way roddick is doing it, planted on the ground with a not so angular swing.
monfils and nishikori do it when they're airborne hitting flashy high backhands but they incorporate more angular rotation than roddick does, neither are planted in the way roddick is, and both coil up with their left leg forward before kicking it back.
ironically, i see more use of this technique(roddick's left leg kick thing) in the ohbh than the twohander, since in the ohbh it's crucial to keep your torso and trunk from opening up too much. on tour, fed and gasquet use it regularly depending on where the ball is in relation to them. it is usually used when an ohbh player doesn't need to or is unable to step into the shot with his dominant leg. that's why it's also common on the ohbh return.
which then leads us back to roddick's weight transfer problem in the video. he has so much time to step in fully (indicated by his early unit turn and stutter steps) and follow through with the left side of his body to get back to open stance(one advantage of the twohander), he doesn't. he's robbing himself of potential power and a quick recovery position.