Wow! Thats a cool explanation. I think I get it. External rotation could lead to bat drag?
I don't listen to Yeager. JMHO. But, show me a successful hitter that external rotates his/her rear humerus.
I know that Harper did in the past but, has since changed....
Up and over not good....
Barry Bonds was a successful hitter ....
So, you're saying Bonds externally rotated his rear humerus on every swing or just on the above gif.
Isn't supination ER of the forearm?