[BCGolf]

As you stated at the TOP the left shoulder is not in a strong position. It is flat and above the swing plane. The right shoulder is in the strong position. Ready to drive down, out, and around on plane. START DOWN is shoulder acceleration, Right shoulder. The right shoulder accelerates and the left shoulder moves in accordance with the right. Check out 1F
As far as linear versus radial force look at 2K, endless belt. Over the years, I have learned to appreciate the importance of the drawings and pictures in the yellow book. The straight side of the belt is linear. Slow steady pressure. The pulley part is radial. Pure acceleration.