Caesars thumb down forehand off hand trick


Just do the "Caesars thumbs down" and you will have a hard time to bend your off hand when hitting a forehand, but ofcourse keep the other fingers also in the natural stretched position and spread them. I think many of you know this but there might be someone who does not. Why not simplify things if we can?
Its just a simple trick and it does not need to be as exegarated as this:

Thiem uses this trick. Watch carefully