[YodasLuke]

"Pulling welds the left arm to the chest, and pushing pushes the left arm off the chest."

You are talking about two different times here. When Hitting, the Left Arm should also be welded to the chest at the point in the Swing that the Left Arm is welded to the chest. Otherwise you've started pushing too soon. The two strokes are supposedly geometrically equivalent.

I was assuming he was talking about downstroke, release, and impact, as the swinger maintains #4 in the downstroke. The 4 barrell hitter starts with #4, but the right shoulder becomes a platform in the downstroke from which the right elbow can explode, thus exhausting the pressure in #4.

Additionally, geometric equivalents they are, physical equivalents they are not.