Not been on in a while, but I would venture to say wcoastsoftball is correct. I came back from major shoulder surgery last fall and couldn't find my swing this year. Started researching batting, and Swing Makeover Series on the y-tube was great.
I used to swing slightly down and try to cut the bottom half. After adjusting to swing level across with a slight uppercut at the end, I went from beating up the tee and occasionally one-hopping a 310-315' fence to hitting the fence regularly, and the last session off the tee I hit 10 of my 5 year old 44/375 balls over the fence. That was with just 2 weeks of adopting the tips.
The 2 other things I found lacking was not keeping my hands "up/down", and needing to collapse my rear leg and stride wider more so I could get under the pitch better to swing it up. After that, I'm just working now on hitting the top half of the ball to get a hard liner that stays in the park when it needs to.