Post-impact, the shaft angle is a near mirror image because he maintains his posture while unwinding.

K.J.'S CONSISTENCY SECRET
If you want to understand why Tour pros are so consistent, check out the butt end of K.J. Choi's driver at address and immediately after impact (above). K.J. starts his swing with the club handle pointing at his belt buckle, and he finishes the swing in exactly the same place. It's tough to hit bad shots with that kind of machine-like precision.