This is just my observation. I think when you see a guy who kinda goes "over the falls like this"^^^^^^^which is not exactly not exactly what TM teaches because this guy is using his front leg for more than just balance. Back to my observation. I see this type of posture more often on low off-speed pitches and it appears to me that the batter is ever so slightly early and in an attempt to time the ball they fall into this posture. In other words, many (not all) gifs that show this, would not what the hitter would practice off the tee or at batting practice. Fire away!
My comment were about the gif rdbass posted of I believe Cardinal player(lefty)
He describes it around the 5 minute mark.
https://www.youtube.com/watch?time_continue=318&v=KRWKmmxsK9g