I wouldn't dismiss what they do, chalking it up to the bats. Clearly how they swing is unconventional. But, it has had dramatic results against some of the best programs, and pitchers in college softball. ULL's hitting success has been consistent for years. "Conventional" hitting teams are constantly changing, tinkering, and learning little things each year to be more efficient and consistent. ULL doesn't.
One thing I think is that this is not going to be very effective until probably 14U or better. You might make more consistent contact but it seems with the limited follow through they are relying on the speed of the pitcher to do a lot of work.
I will say that with 2 strikes, DD's team has implemented a similar swing. Usually results in a non-strikeout, and if they do make solid contact, we've had some girls hit balls in gaps....but they're not rolling very far. No split grip though. We are going to work with our slappers on that though. We're intrigued, let's just say that.