From what I've watched there are too many batters with a mostly "upward" swing plane, which leads to strikeouts and pop ups (which we saw a lot of tonight). I've never liked this in fast pitch softball and not a big fan of it in baseball either, but you can make it work in baseball because the ball is thrown from high-to-low. In softball (especially pitchers with a good rise ball) the ball moves from low-to-high which significantly limits the contact opportunity of bat to ball when you have a big upward swing plane.