I was wondering if you ever discussed or written about how the front foot often leaves the ground during the forehand stroke of the top pros yet their front foot stays rooted to the ground on their two handed backhands.
John, to your knowledge, is there any 5000+ fps video of the contact phase for a TS FH?
Frame-by frame analysis of those 4-5 milliseconds would go a long way in defining the size/shape of the actual contact zone/patch along the cross axis('first contact' through exit) and, by comparing a number of samples with initial ball contact on top-mains 1-5, the zone location tolerance for clean hits vs twisters. Purposely omitting bottom mains, because even first touch on M1 will result in severe twist.
Would have put this into the thread, but I'd like to avoid getting into yet another pointless discussion with Povl and the other "hitting below center is better" folks;)