I may have posted this a few years ago.
A batting coach for a club in the Frontier League told me that some of his players came to him swinging lefty during BP, threw RH, and batted RH during game time.
"They had remarkable perception and bat control", he told me. I asked him what was the deal with the BP? He told me that some batting instructor trained many of them to bat left handed during BP, and by doing so, they were less concerned with parking the commissioner's signature out by the bus lot, and more concerned with the discipline of body/hand's control.
The end result transferred itself to that mental awareness in real time, during game time, quality contacts, better placement of the ball upon contact, and a much higher on-base-percentage. "Oh really," I said to myself.
It's that high on-base-percentage that really worries a pitching coach to no end, and has the club's skipper working his pencil all nine innings.
Now to be totally honest, I never heard of such a training method, nor do I know any one, then and now, who has used that method. Sounds interesting enough though.