Hi Brian
Trevino left forearm is like that because he is left handed and he hits the ball with his left hand, he feels like he hit with the back of his left hand and like you said he does power through with the left hand, it is also very good just playing with only his left hand and says he had hit thousands of balls that way and the right hands just along for the ride. he hits almost as far with his left hand as he does with both.
is the yips not as much to do with the mind as it has to do with the body. i think many players get what they call the yips and it down to the mind but i think there are some that its down to problems with feel and control in the body.
don't think there has been enough research done on the whys and wheres of the yips to really know the cause and if its in the mind or the body.
cheers
bill

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