This topic came up again today as I was doing some hitting mechanics work with a HS team here in Washington. Swinging down on the baseball to create backspin does not happen at the Big League level. If you use MLB players as the standard for correct mechanics, then we have to examine what they are doing a little bit closer. It's a tough concept to explain simply in text, but if you have a read of this article I wrote the last time I ran into this philosophy, maybe you can avoid poor instruction in the future.
Swinging Down on the Ball and the Destruction of Your Hitting Mechanics
Original Post