rotating too early. try to wait until hand is lower and more in ptd position before you rotate the torso. also you are taking the racquet a little too far back and it becomes disconnected. it can't catch up to the rotating torso unless you arm it because it has to come from far back. it has to move as a unit.
your racquet is pointing at like 5:30 in ptd. should point more towards 4:30 and 5 like in the fed vid.
look at murray here. he doesn't rotate until racquet is in ptd